diff --git a/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java b/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
index 5fcc474..fa3354d 100644
--- a/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
+++ b/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
@@ -24,7 +24,6 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.context.annotation.SessionScope;
 import org.springframework.web.multipart.MultipartFile;
-import org.springframework.web.server.ResponseStatusException;
 
 import javax.annotation.security.RolesAllowed;
 import java.io.IOException;
@@ -144,8 +143,7 @@ public class Gruppen2Controller {
 
     @RolesAllowed({"ROLE_orga", "ROLE_studentin", "ROLE_actuator)"})
     @GetMapping("/details/{id}")
-    public String showGroupDetails(KeycloakAuthenticationToken token, Model model, @PathVariable("id") Long groupId) throws EventException, ResponseStatusException {
-
+    public String showGroupDetails(KeycloakAuthenticationToken token, Model model, @PathVariable("id") Long groupId) throws EventException {
         model.addAttribute("account", keyCloakService.createAccountFromPrincipal(token));
         Group group = userService.getGroupById(groupId);
         Account account = keyCloakService.createAccountFromPrincipal(token);
@@ -169,7 +167,7 @@ public class Gruppen2Controller {
         User user = new User(account.getName(), account.getGivenname(), account.getFamilyname(), account.getEmail());
         Group group = userService.getGroupById(groupId);
         if (group.getMembers().contains(user)) {
-            return "errorRenameLater"; //hier soll eigentlich auf die bereits beigetretene Gruppe weitergeleitet werden
+            return "error"; //hier soll eigentlich auf die bereits beigetretene Gruppe weitergeleitet werden
         }
         controllerService.addUser(account, groupId);
         return "redirect:/gruppen2/";
diff --git a/src/main/java/mops/gruppen2/controller/MopsController.java b/src/main/java/mops/gruppen2/controller/MopsController.java
index 8e04634..f1027af 100644
--- a/src/main/java/mops/gruppen2/controller/MopsController.java
+++ b/src/main/java/mops/gruppen2/controller/MopsController.java
@@ -21,6 +21,6 @@ public class MopsController {
 
     @GetMapping("*")
     public String defaultLink() {
-        return "errorRenameLater";
+        return "error";
     }
 }
diff --git a/src/main/java/mops/gruppen2/domain/event/UpdateRoleEvent.java b/src/main/java/mops/gruppen2/domain/event/UpdateRoleEvent.java
index cef22bb..6ce1562 100644
--- a/src/main/java/mops/gruppen2/domain/event/UpdateRoleEvent.java
+++ b/src/main/java/mops/gruppen2/domain/event/UpdateRoleEvent.java
@@ -21,10 +21,12 @@ public class UpdateRoleEvent extends Event {
         super(groupId, userId);
         this.newRole = newRole;
     }
+
     @Override
     public void applyEvent(Group group) throws UserNotFoundException {
         if (group.getRoles().containsKey(this.userId)) {
             group.getRoles().put(this.userId, this.newRole);
+            return;
         }
 
         throw new UserNotFoundException(this.getClass().toString());
diff --git a/src/main/java/mops/gruppen2/security/Account.java b/src/main/java/mops/gruppen2/security/Account.java
index 6ba8dc4..b0466b2 100644
--- a/src/main/java/mops/gruppen2/security/Account.java
+++ b/src/main/java/mops/gruppen2/security/Account.java
@@ -7,9 +7,9 @@ import java.util.Set;
 @Value
 public class Account {
 
+    String name; //user_id
     String email;
     String image;
-    String name; //user_id
     String givenname;
     String familyname;
     Set<String> roles;
diff --git a/src/main/java/mops/gruppen2/service/ControllerService.java b/src/main/java/mops/gruppen2/service/ControllerService.java
index 82de815..cd27a39 100644
--- a/src/main/java/mops/gruppen2/service/ControllerService.java
+++ b/src/main/java/mops/gruppen2/service/ControllerService.java
@@ -120,7 +120,11 @@ public class ControllerService {
                 user = member;
             }
         }
-        assert user != null;
+
+        if (user == null) {
+            throw new UserNotFoundException(this.getClass().toString());
+        }
+
         DeleteUserEvent deleteUserEvent = new DeleteUserEvent(groupId, user.getId());
         eventService.saveEvent(deleteUserEvent);
     }
diff --git a/src/main/resources/templates/detailsMember.html b/src/main/resources/templates/detailsMember.html
index 1dbb75f..03436d8 100644
--- a/src/main/resources/templates/detailsMember.html
+++ b/src/main/resources/templates/detailsMember.html
@@ -79,9 +79,9 @@
                     <ul class="list-group-flush" style="background: slategrey"
                         th:each="member : ${group.getMembers()}">
                         <li class="list-group-item" style="background: aliceblue">
-                            <span th:text="${member.getUser_id()}"></span>
+                            <span th:text="${member.getId()}"></span>
                             <span class="badge badge-success"
-                                  th:if='${group.getRoles().get(member.getUser_id()) == admin}'>admin</span>
+                                  th:if='${group.getRoles().get(member.getId()) == admin}'>admin</span>
                         </li>
                     </ul>
                 </div>
diff --git a/src/main/resources/templates/editMembers.html b/src/main/resources/templates/editMembers.html
index 515fd20..edca787 100644
--- a/src/main/resources/templates/editMembers.html
+++ b/src/main/resources/templates/editMembers.html
@@ -73,16 +73,16 @@
                         <tbody class="table-striped">
 
                         <tr th:each="member : ${group.getMembers()}">
-                            <th th:text="${member.getUser_id()}"></th>
+                            <th th:text="${member.getId()}"></th>
                             <td>
-                                <span th:if='${group.getRoles().get(member.getUser_id()) != admin}'>Mitglied</span>
-                                <span th:if='${group.getRoles().get(member.getUser_id()) == admin}'>Admin</span>
+                                <span th:if='${group.getRoles().get(member.getId()) != admin}'>Mitglied</span>
+                                <span th:if='${group.getRoles().get(member.getId()) == admin}'>Admin</span>
                             </td>
                             <td>
                                 <form action="/gruppen2/details/members/changeRole" method="post">
                                     <input th:name="group_id" th:value="${group.getId()}"
                                            type="hidden">
-                                    <input th:name="user_id" th:value="${member.getUser_id()}"
+                                    <input th:name="user_id" th:value="${member.getId()}"
                                            type="hidden">
                                     <button class="btn btn-warning btn-sm" type="submit">Rolle
                                         ändern
@@ -91,7 +91,7 @@
                                 <form action="/gruppen2/details/members/deleteUser" method="post">
                                     <input th:name="group_id" th:value="${group.getId()}"
                                            type="hidden">
-                                    <input th:name="user_id" th:value="${member.getUser_id()}"
+                                    <input th:name="user_id" th:value="${member.getId()}"
                                            type="hidden">
                                     <button class="btn btn-danger btn-sm">Mitglied entfernen
                                     </button>