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 9b1658d3..e54fef71 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
@@ -116,7 +116,7 @@ public class SEBClientConnectionServiceImpl implements SEBClientConnectionServic
 
         return Result.tryCatch(() -> {
 
-            final SEBClientConfig clientConfig = this.sebClientConfigDAO
+            final SEBClientConfig clientConfig = principal == null ? null : this.sebClientConfigDAO
                     .byClientName(principal.getName())
                     .getOr(null);
 
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/proctoring/ZoomProctoringService.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/proctoring/ZoomProctoringService.java
index 3227938b..bdbc606a 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/proctoring/ZoomProctoringService.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/proctoring/ZoomProctoringService.java
@@ -738,7 +738,7 @@ public class ZoomProctoringService implements ExamProctoringService {
             final String ts = Long.toString(System.currentTimeMillis() - 30000);
             final String msg = String.format("%s%s%s%d", apiKey, meetingId, ts, status);
 
-            hasher.init(new SecretKeySpec(decryptedSecret.toString().getBytes(), "HmacSHA256"));
+            hasher.init(new SecretKeySpec(Utils.toByteArray(decryptedSecret), "HmacSHA256"));
 
             final String message = Base64.getEncoder().encodeToString(msg.getBytes());
             final byte[] hash = hasher.doFinal(message.getBytes());
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ClientConnectionController.java b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ClientConnectionController.java
index 8973f4cd..807a0b51 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ClientConnectionController.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ClientConnectionController.java
@@ -323,7 +323,7 @@ public class ClientConnectionController extends ReadonlyEntityController<ClientC
                     final int result = indicatorValue1.compareTo(indicatorValue2);
                     return (this.clientConnectionComparator.descending) ? -result : result;
                 } catch (final Exception e) {
-                    this.clientConnectionComparator.compare(cc1.clientConnection, cc2.clientConnection);
+                    return this.clientConnectionComparator.compare(cc1.clientConnection, cc2.clientConnection);
                 }
             }
 
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
index 8e6aa53f..944d6874 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
@@ -9,6 +9,7 @@
 package ch.ethz.seb.sebserver.webservice.weblayer.api;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.security.Principal;
 import java.util.Arrays;
 import java.util.Collection;
@@ -299,19 +300,9 @@ public class ExamAPI_V1_Controller {
     public void ping(final HttpServletRequest request, final HttpServletResponse response) {
 
         final String connectionToken = request.getHeader(API.EXAM_API_SEB_CONNECTION_TOKEN);
-        //final String timeStampString = request.getParameter(API.EXAM_API_PING_TIMESTAMP);
         final String pingNumString = request.getParameter(API.EXAM_API_PING_NUMBER);
         final String instructionConfirm = request.getParameter(API.EXAM_API_PING_INSTRUCTION_CONFIRM);
 
-//        long pingTime;
-//        try {
-//            pingTime = Long.parseLong(timeStampString);
-//        } catch (final Exception e) {
-//            log.error("Invalid ping request: {}", connectionToken);
-//            response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
-//            return;
-//        }
-
         final String instruction = this.sebClientConnectionService
                 .notifyPing(
                         connectionToken,
@@ -324,7 +315,7 @@ public class ExamAPI_V1_Controller {
         } else {
             try {
                 response.setStatus(HttpStatus.OK.value());
-                response.getOutputStream().write(instruction.getBytes());
+                response.getOutputStream().write(instruction.getBytes(StandardCharsets.UTF_8));
             } catch (final IOException e) {
                 log.error("Failed to send instruction as response: {}", connectionToken, e);
             }