diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/BatchActionDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/BatchActionDAOImpl.java
index 94b99627..6956dad4 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/BatchActionDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/BatchActionDAOImpl.java
@@ -13,6 +13,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.*;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -212,14 +213,20 @@ public class BatchActionDAOImpl implements BatchActionDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<BatchAction>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.batchActionRecordMapper.selectByExample()
-                .where(BatchActionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.batchActionRecordMapper.selectByExample()
+                    .where(BatchActionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -293,6 +300,10 @@ public class BatchActionDAOImpl implements BatchActionDAO {
 
             final List<Long> ids = extractListOfPKs(all);
 
+            if (ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             this.batchActionRecordMapper.deleteByExample()
                     .where(BatchActionRecordDynamicSqlSupport.id, isIn(ids))
                     .build()
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientConnectionDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientConnectionDAOImpl.java
index e4435cd7..17d73500 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientConnectionDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientConnectionDAOImpl.java
@@ -141,7 +141,7 @@ public class ClientConnectionDAOImpl implements ClientConnectionDAO {
     @Transactional(readOnly = true)
     public Result<Collection<ClientConnection>> allOf(final Set<Long> pks) {
         if (pks == null || pks.isEmpty()) {
-            return Result.ofRuntimeError("Null or empty set reference");
+            return Result.of(Collections.emptyList());
         }
         return Result.tryCatch(() -> this.clientConnectionRecordMapper.selectByExample()
                 .where(ClientConnectionRecordDynamicSqlSupport.id, SqlBuilder.isIn(new ArrayList<>(pks)))
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientEventDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientEventDAOImpl.java
index 4f45949a..e073bab0 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientEventDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ClientEventDAOImpl.java
@@ -13,6 +13,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.*;
 import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Predicate;
@@ -186,14 +187,21 @@ public class ClientEventDAOImpl implements ClientEventDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ClientEvent>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.clientEventRecordMapper.selectByExample()
-                .where(ClientEventRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ClientEventDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.clientEventRecordMapper.selectByExample()
+                    .where(ClientEventRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ClientEventDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -378,6 +386,10 @@ public class ClientEventDAOImpl implements ClientEventDAO {
     public Result<Collection<EntityKey>> delete(final Set<EntityKey> all) {
         return Result.tryCatch(() -> {
 
+            if (all == null || all.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final List<Long> pks = all
                     .stream()
                     .map(EntityKey::getModelId)
@@ -402,12 +414,20 @@ public class ClientEventDAOImpl implements ClientEventDAO {
     public Result<Collection<EntityKey>> deleteClientNotification(final Set<EntityKey> keys) {
         return Result.tryCatch(() -> {
 
+            if (keys == null || keys.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final List<Long> pks = keys
                     .stream()
                     .map(EntityKey::getModelId)
                     .map(Long::parseLong)
                     .collect(Collectors.toList());
 
+            if (log.isDebugEnabled()) {
+                log.debug("Going to delete all client notifications: {}", pks);
+            }
+
             this.clientNotificationRecordMapper
                     .deleteByExample()
                     .where(ClientNotificationRecordDynamicSqlSupport.id, isIn(pks))
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationAttributeDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationAttributeDAOImpl.java
index ea907528..cc3b6697 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationAttributeDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationAttributeDAOImpl.java
@@ -12,6 +12,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.isIn;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Predicate;
@@ -75,14 +76,21 @@ public class ConfigurationAttributeDAOImpl implements ConfigurationAttributeDAO
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ConfigurationAttribute>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.configurationAttributeRecordMapper.selectByExample()
-                .where(ConfigurationAttributeRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ConfigurationAttributeDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.configurationAttributeRecordMapper.selectByExample()
+                    .where(ConfigurationAttributeRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ConfigurationAttributeDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -191,6 +199,10 @@ public class ConfigurationAttributeDAOImpl implements ConfigurationAttributeDAO
             final List<Long> ids = extractListOfPKs(all);
             final List<EntityKey> result = new ArrayList<>();
 
+            if (ids == null || ids.isEmpty()) {
+                return result;
+            }
+
             // if this is a complex attribute that has children, delete the children first
             final List<ConfigurationAttributeRecord> children =
                     this.configurationAttributeRecordMapper.selectByExample()
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOBatchService.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOBatchService.java
index af4d7658..a7790ca7 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOBatchService.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOBatchService.java
@@ -552,15 +552,17 @@ class ConfigurationDAOBatchService {
                 .collect(Collectors.toList());
 
         // first delete all old values of this table
-        this.batchConfigurationValueRecordMapper.deleteByExample()
-                .where(
-                        ConfigurationValueRecordDynamicSqlSupport.configurationId,
-                        isEqualTo(value.configurationId))
-                .and(
-                        ConfigurationValueRecordDynamicSqlSupport.configurationAttributeId,
-                        SqlBuilder.isIn(columnAttributeIds))
-                .build()
-                .execute();
+        if (!columnAttributeIds.isEmpty()) {
+            this.batchConfigurationValueRecordMapper.deleteByExample()
+                    .where(
+                            ConfigurationValueRecordDynamicSqlSupport.configurationId,
+                            isEqualTo(value.configurationId))
+                    .and(
+                            ConfigurationValueRecordDynamicSqlSupport.configurationAttributeId,
+                            SqlBuilder.isIn(columnAttributeIds))
+                    .build()
+                    .execute();
+        }
 
         // then add the new values
         for (final TableValue tableValue : value.values) {
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOImpl.java
index a76b57a1..5ce765ff 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationDAOImpl.java
@@ -8,6 +8,22 @@
 
 package ch.ethz.seb.sebserver.webservice.servicelayer.dao.impl;
 
+import static org.mybatis.dynamic.sql.SqlBuilder.*;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+import org.apache.commons.lang3.BooleanUtils;
+import org.springframework.context.annotation.Lazy;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Propagation;
+import org.springframework.transaction.annotation.Transactional;
+
 import ch.ethz.seb.sebserver.gbl.api.EntityType;
 import ch.ethz.seb.sebserver.gbl.model.sebconfig.Configuration;
 import ch.ethz.seb.sebserver.gbl.profile.WebServiceProfile;
@@ -23,20 +39,6 @@ import ch.ethz.seb.sebserver.webservice.servicelayer.dao.DAOLoggingSupport;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.FilterMap;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.ResourceNotFoundException;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.TransactionHandler;
-import org.apache.commons.lang3.BooleanUtils;
-import org.springframework.context.annotation.Lazy;
-import org.springframework.stereotype.Component;
-import org.springframework.transaction.annotation.Propagation;
-import org.springframework.transaction.annotation.Transactional;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
-import java.util.Set;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-
-import static org.mybatis.dynamic.sql.SqlBuilder.*;
 
 @Lazy
 @Component
@@ -72,14 +74,21 @@ public class ConfigurationDAOImpl implements ConfigurationDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<Configuration>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.configurationRecordMapper.selectByExample()
-                .where(ConfigurationRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ConfigurationDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.configurationRecordMapper.selectByExample()
+                    .where(ConfigurationRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ConfigurationDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationNodeDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationNodeDAOImpl.java
index 489c511b..f55032d5 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationNodeDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationNodeDAOImpl.java
@@ -91,14 +91,21 @@ public class ConfigurationNodeDAOImpl implements ConfigurationNodeDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ConfigurationNode>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.configurationNodeRecordMapper.selectByExample()
-                .where(ConfigurationNodeRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ConfigurationNodeDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.configurationNodeRecordMapper.selectByExample()
+                    .where(ConfigurationNodeRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ConfigurationNodeDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -225,6 +232,10 @@ public class ConfigurationNodeDAOImpl implements ConfigurationNodeDAO {
 
             final List<Long> ids = extractListOfPKs(all);
 
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             // find all configurations for this configuration node
             final List<Long> configurationIds = this.configurationRecordMapper.selectIdsByExample()
                     .where(ConfigurationRecordDynamicSqlSupport.configurationNodeId, isIn(ids))
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationValueDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationValueDAOImpl.java
index a405c450..1bfbcc7c 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationValueDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ConfigurationValueDAOImpl.java
@@ -11,7 +11,17 @@ package ch.ethz.seb.sebserver.webservice.servicelayer.dao.impl;
 import static org.mybatis.dynamic.sql.SqlBuilder.isEqualTo;
 import static org.mybatis.dynamic.sql.SqlBuilder.isIn;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -115,14 +125,21 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ConfigurationValue>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.configurationValueRecordMapper.selectByExample()
-                .where(ConfigurationValueRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ConfigurationValueDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.configurationValueRecordMapper.selectByExample()
+                    .where(ConfigurationValueRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ConfigurationValueDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -248,6 +265,9 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
                 .flatMap(this::getAttributeMapping)
                 .map(attributeMapping -> {
                     // get all values of the table
+                    final ArrayList<Long> attrs = (attributeMapping != null && !attributeMapping.isEmpty())
+                            ? new ArrayList<>(attributeMapping.keySet())
+                            : null;
                     final List<TableValue> values = this.configurationValueRecordMapper.selectByExample()
                             .where(
                                     ConfigurationValueRecordDynamicSqlSupport.institutionId,
@@ -257,7 +277,7 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
                                     isEqualTo(configurationId))
                             .and(
                                     ConfigurationValueRecordDynamicSqlSupport.configurationAttributeId,
-                                    SqlBuilder.isIn(new ArrayList<>(attributeMapping.keySet())))
+                                    SqlBuilder.isInWhenPresent(attrs))
                             .build()
                             .execute()
                             .stream()
@@ -329,13 +349,13 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
             rows.sort(Comparator.naturalOrder());
             rows.forEach(i -> {
 
-                        final Map<Long, ConfigurationValue> rowValuesMapping = indexMapping.get(i);
-                        final List<ConfigurationValue> rowValues = attributes
-                                .stream()
-                                .map(attr -> rowValuesMapping.get(attr.getId()))
-                                .collect(Collectors.toList());
-                        result.add(rowValues);
-                    });
+                final Map<Long, ConfigurationValue> rowValuesMapping = indexMapping.get(i);
+                final List<ConfigurationValue> rowValues = attributes
+                        .stream()
+                        .map(attr -> rowValuesMapping.get(attr.getId()))
+                        .collect(Collectors.toList());
+                result.add(rowValues);
+            });
 
             return result;
         });
@@ -362,7 +382,9 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
 
                     final Set<EntityKey> tableValues = new HashSet<>();
                     if (attributeMapping != null && !attributeMapping.isEmpty()) {
-
+                        final ArrayList<Long> attrs = (attributeMapping != null && !attributeMapping.isEmpty())
+                                ? new ArrayList<>(attributeMapping.keySet())
+                                : null;
                         tableValues.addAll(this.configurationValueRecordMapper.selectByExample()
                                 .where(
                                         ConfigurationValueRecordDynamicSqlSupport.institutionId,
@@ -372,7 +394,7 @@ public class ConfigurationValueDAOImpl implements ConfigurationValueDAO {
                                         isEqualTo(configurationId))
                                 .and(
                                         ConfigurationValueRecordDynamicSqlSupport.configurationAttributeId,
-                                        SqlBuilder.isIn(new ArrayList<>(attributeMapping.keySet())))
+                                        SqlBuilder.isInWhenPresent(attrs))
                                 .build()
                                 .execute()
                                 .stream()
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamConfigurationMapDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamConfigurationMapDAOImpl.java
index 358ed409..75554471 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamConfigurationMapDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamConfigurationMapDAOImpl.java
@@ -98,14 +98,21 @@ public class ExamConfigurationMapDAOImpl implements ExamConfigurationMapDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ExamConfigurationMap>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.examConfigurationMapRecordMapper.selectByExample()
-                .where(ExamConfigurationMapRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.examConfigurationMapRecordMapper.selectByExample()
+                    .where(ExamConfigurationMapRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -268,6 +275,9 @@ public class ExamConfigurationMapDAOImpl implements ExamConfigurationMapDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             // get all involved configurations
             final List<Long> configIds = this.examConfigurationMapRecordMapper.selectByExample()
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamDAOImpl.java
index 1354e23d..b9d997e4 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamDAOImpl.java
@@ -217,6 +217,10 @@ public class ExamDAOImpl implements ExamDAO {
         final Result<Collection<EntityKey>> tryCatch = Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final ExamRecord examRecord = new ExamRecord(null, null, null, null, null,
                     null, null, null, null, null, null, null, null, BooleanUtils.toInteger(active), null,
                     Utils.getMillisecondsNow());
@@ -484,6 +488,9 @@ public class ExamDAOImpl implements ExamDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             // notify exam deletion listener about following deletion, to cleanup stuff before deletion
             this.applicationEventPublisher.publishEvent(new ExamDeletionEvent(ids));
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamRecordDAO.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamRecordDAO.java
index 45afbbb0..e02aa7eb 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamRecordDAO.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamRecordDAO.java
@@ -12,6 +12,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.*;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -330,10 +331,17 @@ public class ExamRecordDAO {
 
     @Transactional(readOnly = true)
     public Result<Collection<ExamRecord>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.examRecordMapper.selectByExample()
-                .where(ExamRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute());
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.examRecordMapper.selectByExample()
+                    .where(ExamRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute();
+        });
     }
 
 }
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamTemplateDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamTemplateDAOImpl.java
index 7d369aca..ce75daa1 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamTemplateDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamTemplateDAOImpl.java
@@ -117,14 +117,21 @@ public class ExamTemplateDAOImpl implements ExamTemplateDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<ExamTemplate>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.examTemplateRecordMapper.selectByExample()
-                .where(IndicatorRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.examTemplateRecordMapper.selectByExample()
+                    .where(IndicatorRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -247,6 +254,9 @@ public class ExamTemplateDAOImpl implements ExamTemplateDAO {
             log.info("Delete exam templates: {}", all);
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             ids.stream()
                     .forEach(id -> {
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/IndicatorDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/IndicatorDAOImpl.java
index 9d465923..82f92564 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/IndicatorDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/IndicatorDAOImpl.java
@@ -105,14 +105,21 @@ public class IndicatorDAOImpl implements IndicatorDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<Indicator>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.indicatorRecordMapper.selectByExample()
-                .where(IndicatorRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.indicatorRecordMapper.selectByExample()
+                    .where(IndicatorRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -193,6 +200,9 @@ public class IndicatorDAOImpl implements IndicatorDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             // first delete all thresholds of indicators
             this.thresholdRecordMapper.deleteByExample()
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/InstitutionDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/InstitutionDAOImpl.java
index a0bcedc7..15dcbf30 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/InstitutionDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/InstitutionDAOImpl.java
@@ -170,6 +170,10 @@ public class InstitutionDAOImpl implements InstitutionDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final InstitutionRecord institutionRecord = new InstitutionRecord(
                     null, null, null, null, BooleanUtils.toInteger(active), null);
 
@@ -204,6 +208,9 @@ public class InstitutionDAOImpl implements InstitutionDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.institutionRecordMapper.deleteByExample()
                     .where(InstitutionRecordDynamicSqlSupport.id, isIn(ids))
@@ -226,14 +233,21 @@ public class InstitutionDAOImpl implements InstitutionDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<Institution>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.institutionRecordMapper.selectByExample()
-                .where(InstitutionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(InstitutionDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.institutionRecordMapper.selectByExample()
+                    .where(InstitutionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(InstitutionDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     private Result<InstitutionRecord> recordById(final Long id) {
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/LmsSetupDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/LmsSetupDAOImpl.java
index 153a83a5..4a69787c 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/LmsSetupDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/LmsSetupDAOImpl.java
@@ -241,6 +241,10 @@ public class LmsSetupDAOImpl implements LmsSetupDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final LmsSetupRecord lmsSetupRecord = new LmsSetupRecord(
                     null, null, null, null, null, null, null, null, null, null, null, null,
                     System.currentTimeMillis(),
@@ -277,6 +281,9 @@ public class LmsSetupDAOImpl implements LmsSetupDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.lmsSetupRecordMapper.deleteByExample()
                     .where(LmsSetupRecordDynamicSqlSupport.id, isIn(ids))
@@ -303,14 +310,21 @@ public class LmsSetupDAOImpl implements LmsSetupDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<LmsSetup>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.lmsSetupRecordMapper.selectByExample()
-                .where(LmsSetupRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.lmsSetupRecordMapper.selectByExample()
+                    .where(LmsSetupRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/OrientationDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/OrientationDAOImpl.java
index aff14a17..65e8dd36 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/OrientationDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/OrientationDAOImpl.java
@@ -13,6 +13,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.isIn;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -68,14 +69,21 @@ public class OrientationDAOImpl implements OrientationDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<Orientation>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.orientationRecordMapper.selectByExample()
-                .where(OrientationRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(OrientationDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.orientationRecordMapper.selectByExample()
+                    .where(OrientationRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(OrientationDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -227,6 +235,9 @@ public class OrientationDAOImpl implements OrientationDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.orientationRecordMapper.deleteByExample()
                     .where(OrientationRecordDynamicSqlSupport.id, isIn(ids))
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/SEBClientConfigDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/SEBClientConfigDAOImpl.java
index 8175572e..3ef769f6 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/SEBClientConfigDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/SEBClientConfigDAOImpl.java
@@ -196,6 +196,10 @@ public class SEBClientConfigDAOImpl implements SEBClientConfigDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final SebClientConfigRecord record = new SebClientConfigRecord(
                     null, null, null, null, null, null, null,
                     BooleanUtils.toIntegerObject(active));
@@ -278,6 +282,9 @@ public class SEBClientConfigDAOImpl implements SEBClientConfigDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.sebClientConfigRecordMapper.deleteByExample()
                     .where(SebClientConfigRecordDynamicSqlSupport.id, isIn(ids))
@@ -293,14 +300,21 @@ public class SEBClientConfigDAOImpl implements SEBClientConfigDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<SEBClientConfig>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.sebClientConfigRecordMapper.selectByExample()
-                .where(SebClientConfigRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.sebClientConfigRecordMapper.selectByExample()
+                    .where(SebClientConfigRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserActivityLogDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserActivityLogDAOImpl.java
index a511c5df..23c6f586 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserActivityLogDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserActivityLogDAOImpl.java
@@ -324,6 +324,9 @@ public class UserActivityLogDAOImpl implements UserActivityLogDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.userLogRecordMapper.deleteByExample()
                     .where(UserActivityLogRecordDynamicSqlSupport.id, isIn(ids))
@@ -438,12 +441,19 @@ public class UserActivityLogDAOImpl implements UserActivityLogDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<UserActivityLog>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.toDomainModel(
-                this.userService.getCurrentUser().institutionId(),
-                this.userLogRecordMapper.selectByExample()
-                        .where(UserActivityLogRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                        .build()
-                        .execute()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.toDomainModel(
+                    this.userService.getCurrentUser().institutionId(),
+                    this.userLogRecordMapper.selectByExample()
+                            .where(UserActivityLogRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                            .build()
+                            .execute());
+        });
     }
 
     @Override
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserDAOImpl.java
index fec7fb1a..fb0a9f82 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/UserDAOImpl.java
@@ -324,6 +324,10 @@ public class UserDAOImpl implements UserDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
+
             final UserRecord userRecord = new UserRecord(
                     null, null, null, null, null, null, null, null, null, null, null,
                     BooleanUtils.toIntegerObject(active));
@@ -363,6 +367,9 @@ public class UserDAOImpl implements UserDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             // get all user records for later processing
             final List<UserRecord> users = this.userRecordMapper.selectByExample()
@@ -413,14 +420,21 @@ public class UserDAOImpl implements UserDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<UserInfo>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.userRecordMapper.selectByExample()
-                .where(InstitutionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(this::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.userRecordMapper.selectByExample()
+                    .where(InstitutionRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(this::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -429,6 +443,11 @@ public class UserDAOImpl implements UserDAO {
             return UserDAO.super.extractPKsFromKeys(keys);
         } else {
             try {
+
+                if (keys == null || keys.isEmpty()) {
+                    return Collections.emptySet();
+                }
+
                 final List<String> uuids = keys.stream()
                         .map(key -> key.modelId)
                         .collect(Collectors.toList());
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ViewDAOImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ViewDAOImpl.java
index 49f8d02c..02e7ab4c 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ViewDAOImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ViewDAOImpl.java
@@ -12,6 +12,7 @@ import static org.mybatis.dynamic.sql.SqlBuilder.isIn;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -65,14 +66,21 @@ public class ViewDAOImpl implements ViewDAO {
     @Override
     @Transactional(readOnly = true)
     public Result<Collection<View>> allOf(final Set<Long> pks) {
-        return Result.tryCatch(() -> this.viewRecordMapper.selectByExample()
-                .where(ViewRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
-                .build()
-                .execute()
-                .stream()
-                .map(ViewDAOImpl::toDomainModel)
-                .flatMap(DAOLoggingSupport::logAndSkipOnError)
-                .collect(Collectors.toList()));
+        return Result.tryCatch(() -> {
+
+            if (pks == null || pks.isEmpty()) {
+                return Collections.emptyList();
+            }
+
+            return this.viewRecordMapper.selectByExample()
+                    .where(ViewRecordDynamicSqlSupport.id, isIn(new ArrayList<>(pks)))
+                    .build()
+                    .execute()
+                    .stream()
+                    .map(ViewDAOImpl::toDomainModel)
+                    .flatMap(DAOLoggingSupport::logAndSkipOnError)
+                    .collect(Collectors.toList());
+        });
     }
 
     @Override
@@ -212,6 +220,9 @@ public class ViewDAOImpl implements ViewDAO {
         return Result.tryCatch(() -> {
 
             final List<Long> ids = extractListOfPKs(all);
+            if (ids == null || ids.isEmpty()) {
+                return Collections.emptyList();
+            }
 
             this.viewRecordMapper.deleteByExample()
                     .where(ViewRecordDynamicSqlSupport.id, isIn(ids))
diff --git a/src/main/resources/messages.properties b/src/main/resources/messages.properties
index 109637e6..54a35747 100644
--- a/src/main/resources/messages.properties
+++ b/src/main/resources/messages.properties
@@ -282,7 +282,7 @@ sebserver.useraccount.delete.form.deleteExams.tooltip=This includes all Exams wh
 sebserver.useraccount.delete.form.action.delete=Delete
 sebserver.useraccount.delete.form.action.report=Show Report
 sebserver.useraccount.delete.confirm.title=Deletion Successful
-sebserver.useraccount.delete.confirm.message=The User Account ({0}) was successfully deleted.<br/>Also the following number dependencies where successfully deleted: {1}.<br/><br/>And there where {2} errors.
+sebserver.useraccount.delete.confirm.message=The User Account ({0}) was successfully deleted.<br/>Also the following number of dependencies where successfully deleted: {1}.<br/><br/>And there where {2} errors.
 sebserver.useraccount.delete.confirm.message.noDeps=The User Account ({0}) was successfully deleted.
 ################################
 # LMS Setup