diff --git a/src/main/java/ch/ethz/seb/sebserver/gui/content/exam/ExamDeletePopup.java b/src/main/java/ch/ethz/seb/sebserver/gui/content/exam/ExamDeletePopup.java
index 90edacaa..4a403ac6 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gui/content/exam/ExamDeletePopup.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gui/content/exam/ExamDeletePopup.java
@@ -26,16 +26,20 @@ import org.springframework.stereotype.Component;
 
 import ch.ethz.seb.sebserver.gbl.api.API;
 import ch.ethz.seb.sebserver.gbl.api.API.BulkActionType;
+import ch.ethz.seb.sebserver.gbl.api.APIMessage;
+import ch.ethz.seb.sebserver.gbl.api.APIMessage.ErrorMessage;
 import ch.ethz.seb.sebserver.gbl.model.EntityDependency;
 import ch.ethz.seb.sebserver.gbl.model.EntityKey;
 import ch.ethz.seb.sebserver.gbl.model.EntityProcessingReport;
 import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
 import ch.ethz.seb.sebserver.gbl.profile.GuiProfile;
+import ch.ethz.seb.sebserver.gbl.util.Result;
 import ch.ethz.seb.sebserver.gbl.util.Utils;
 import ch.ethz.seb.sebserver.gui.content.action.ActionDefinition;
 import ch.ethz.seb.sebserver.gui.service.i18n.I18nSupport;
 import ch.ethz.seb.sebserver.gui.service.i18n.LocTextKey;
 import ch.ethz.seb.sebserver.gui.service.page.PageContext;
+import ch.ethz.seb.sebserver.gui.service.page.PageMessageException;
 import ch.ethz.seb.sebserver.gui.service.page.PageService;
 import ch.ethz.seb.sebserver.gui.service.page.event.ActionEvent;
 import ch.ethz.seb.sebserver.gui.service.page.impl.ModalInputWizard;
@@ -43,6 +47,7 @@ import ch.ethz.seb.sebserver.gui.service.page.impl.ModalInputWizard.WizardAction
 import ch.ethz.seb.sebserver.gui.service.page.impl.ModalInputWizard.WizardPage;
 import ch.ethz.seb.sebserver.gui.service.page.impl.PageAction;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.RestCall;
+import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.RestCallError;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.exam.DeleteExam;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.exam.GetExam;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.exam.GetExamDependencies;
@@ -76,6 +81,8 @@ public class ExamDeletePopup {
 
     private final static LocTextKey DELETE_CONFIRM_TITLE =
             new LocTextKey("sebserver.exam.delete.confirm.title");
+    private final static LocTextKey DELETE_ERROR_CONSISTENCY =
+            new LocTextKey("sebserver.exam.action.delete.consistency.error");
 
     private final PageService pageService;
 
@@ -126,7 +133,23 @@ public class ExamDeletePopup {
                     .withURIVariable(API.PARAM_MODEL_ID, entityKey.modelId)
                     .withQueryParam(API.PARAM_BULK_ACTION_TYPE, BulkActionType.HARD_DELETE.name());
 
-            final EntityProcessingReport report = restCallBuilder.call().getOrThrow();
+            final Result<EntityProcessingReport> deleteCall = restCallBuilder.call();
+            if (deleteCall.hasError()) {
+                final Exception error = deleteCall.getError();
+                if (error instanceof RestCallError) {
+                    final APIMessage message = ((RestCallError) error)
+                            .getAPIMessages()
+                            .stream()
+                            .findFirst()
+                            .orElse(null);
+                    if (message != null && ErrorMessage.INTEGRITY_VALIDATION.isOf(message)) {
+                        pageContext.publishPageMessage(new PageMessageException(DELETE_ERROR_CONSISTENCY));
+                        return false;
+                    }
+                }
+            }
+
+            final EntityProcessingReport report = deleteCall.getOrThrow();
 
             final PageAction action = this.pageService.pageActionBuilder(pageContext)
                     .newAction(ActionDefinition.EXAM_VIEW_LIST)
diff --git a/src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java b/src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java
index 2e61b70a..7a8053d0 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java
@@ -293,8 +293,13 @@ public final class ClientConnectionTable {
         final Set<EntityKey> result = new HashSet<>();
         for (int i = 0; i < selectionIndices.length; i++) {
             final UpdatableTableItem updatableTableItem =
-                    new ArrayList<>(this.tableMapping.values()).get(selectionIndices[0]);
-            result.add(new EntityKey(updatableTableItem.connectionId, EntityType.CLIENT_CONNECTION));
+                    new ArrayList<>(this.tableMapping.values())
+                            .stream()
+                            .findFirst()
+                            .orElse(null);
+            if (updatableTableItem != null) {
+                result.add(new EntityKey(updatableTableItem.connectionId, EntityType.CLIENT_CONNECTION));
+            }
         }
         return result;
     }
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/bulkaction/impl/BulkActionServiceImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/bulkaction/impl/BulkActionServiceImpl.java
index 1af2f322..b165d44c 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/bulkaction/impl/BulkActionServiceImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/bulkaction/impl/BulkActionServiceImpl.java
@@ -166,8 +166,8 @@ public class BulkActionServiceImpl implements BulkActionService {
         final Exception error = bulkActionSingleResult.getError();
 
         log.error(
-                "Unexpected error on bulk action processing. This error is reported to the caller: {}",
-                error.getMessage());
+                "Unexpected error on bulk action processing. This error is reported to the caller: ",
+                error);
 
         if (error instanceof BulkActionEntityException) {
             return new ErrorEntry(
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientConnectionServiceImpl.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientConnectionServiceImpl.java
index b7573107..3cc98368 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientConnectionServiceImpl.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientConnectionServiceImpl.java
@@ -673,10 +673,15 @@ public class SEBClientConnectionServiceImpl implements SEBClientConnectionServic
             final Long examId) {
 
         if (StringUtils.isNotBlank(userSessionId)) {
-            if (StringUtils.isNoneBlank(clientConnection.userSessionId)) {
-                log.warn(
-                        "ClientConnection integrity violation: clientConnection has already a userSessionId: {} : {}",
-                        userSessionId, clientConnection);
+
+            if (StringUtils.isNoneBlank(clientConnection.userSessionId)
+                    && clientConnection.userSessionId.contains(userSessionId)) {
+
+                if (log.isDebugEnabled()) {
+                    log.debug("SEB sent LMS userSessionId but clientConnection has already a userSessionId");
+                }
+
+                return clientConnection;
             }
 
             // try to get user account display name
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/EntityController.java b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/EntityController.java
index 1ccc0c94..c3471521 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/EntityController.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/EntityController.java
@@ -376,9 +376,15 @@ public abstract class EntityController<T extends Entity, M extends Entity> {
         }
 
         final EntityType entityType = this.entityDAO.entityType();
-        final Collection<EntityKey> sources = ids
-                .stream()
-                .map(this::logDelete)
+
+        final Collection<EntityKey> sources = ids.stream()
+                .map(id -> {
+                    return this.entityDAO.byModelId(id)
+                            .flatMap(exam -> this.validForDelete(exam))
+                            .getOr(null);
+                })
+                .filter(Objects::nonNull)
+                .map(exam -> exam.getModelId())
                 .map(id -> new EntityKey(id, entityType))
                 .collect(Collectors.toList());
 
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAdministrationController.java b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAdministrationController.java
index ada43c21..40f9229d 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAdministrationController.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAdministrationController.java
@@ -500,6 +500,11 @@ public class ExamAdministrationController extends EntityController<Exam, Exam> {
         }
     }
 
+    @Override
+    protected Result<Exam> validForDelete(final Exam entity) {
+        return checkNoActiveSEBClientConnections(entity);
+    }
+
     private Exam checkExamSupporterRole(final Exam exam) {
         final Set<String> examSupporter = this.userDAO.all(
                 this.authorization.getUserService().getCurrentUser().getUserInfo().institutionId,
diff --git a/src/main/resources/messages.properties b/src/main/resources/messages.properties
index fec5fc40..e80ee182 100644
--- a/src/main/resources/messages.properties
+++ b/src/main/resources/messages.properties
@@ -457,6 +457,7 @@ sebserver.exam.action.save=Save Exam
 sebserver.exam.action.activate=Activate Exam
 sebserver.exam.action.deactivate=Deactivate Exam
 sebserver.exam.action.delete=Delete Exam
+sebserver.exam.action.delete.consistency.error=Deletion Failed.<br/>Please make sure there are no active SEB clients connected to the exam before deletion.
 sebserver.exam.action.sebrestriction.enable=Apply SEB Lock
 sebserver.exam.action.sebrestriction.disable=Release SEB Lock
 sebserver.exam.action.sebrestriction.details=SEB Restriction Details