diff --git a/lib/Manager/ACLManager.php b/lib/Manager/ACLManager.php
index 6036fb8..bbb6aa2 100644
--- a/lib/Manager/ACLManager.php
+++ b/lib/Manager/ACLManager.php
@@ -16,6 +16,8 @@ use OCA\GroupFolders\Folder\FolderManager;
 use OCA\OrganizationFolders\OrganizationProvider\OrganizationProviderManager;
 use OCA\OrganizationFolders\Model\Principal;
 use OCA\OrganizationFolders\Enum\PrincipalType;
+use OCA\OrganizationFolders\Errors\OrganizationProviderNotFound;
+use OCA\OrganizationFolders\Errors\OrganizationRoleNotFound;
 
 class ACLManager {
     public function __construct(
@@ -54,7 +56,7 @@ class ACLManager {
         return array_map($this->createRuleEntityFromRow(...), $rows);
     }
 
-    public function getMappingForPrincipal(Principal $principal): IUserMapping {
+    public function getMappingForPrincipal(Principal $principal): ?IUserMapping {
         if($principal->getType() === PrincipalType::USER) {
             return $this->userMappingManager->mappingFromId("user", $principal->getId());
         } else if($principal->getType() === PrincipalType::GROUP) {
@@ -62,8 +64,17 @@ class ACLManager {
         } else if($principal->getType() === PrincipalType::ROLE) {
             [$organizationProviderId, $roleId] = explode(":", $principal->getId(), 2);
 
-            $organizationProvider = $this->organizationProviderManager->getOrganizationProvider($organizationProviderId);
-            $role = $organizationProvider->getRole($roleId);
+            try {
+                $organizationProvider = $this->organizationProviderManager->getOrganizationProvider($organizationProviderId);
+            } catch (OrganizationProviderNotFound $e) {
+                return null;
+            }
+            
+            try {
+                $role = $organizationProvider->getRole($roleId);
+            } catch (OrganizationRoleNotFound $e) {
+                return null;
+            }
 
             return $this->userMappingManager->mappingFromId("group", $role->getMembersGroup());
         } else {
diff --git a/lib/Service/ResourceMemberService.php b/lib/Service/ResourceMemberService.php
index 2ae7315..12a19e0 100644
--- a/lib/Service/ResourceMemberService.php
+++ b/lib/Service/ResourceMemberService.php
@@ -32,10 +32,10 @@ class ResourceMemberService {
 		return $this->mapper->findAll($resourceId);
 	}
 
-	private function handleException(Exception $e): void {
+	private function handleException(Exception $e, int $id): void {
 		if ($e instanceof DoesNotExistException ||
 			$e instanceof MultipleObjectsReturnedException) {
-			throw new ResourceMemberNotFound($e->getMessage());
+			throw new ResourceMemberNotFound($id);
 		} else {
 			throw $e;
 		}
@@ -45,7 +45,7 @@ class ResourceMemberService {
 		try {
 			return $this->mapper->find($id);
 		} catch (Exception $e) {
-			$this->handleException($e);
+			$this->handleException($e, $id);
 		}
 	}
 
@@ -96,7 +96,7 @@ class ResourceMemberService {
 
 			return $member;
 		} catch (Exception $e) {
-			$this->handleException($e);
+			$this->handleException($e, $id);
 		}
 	}
 
@@ -111,7 +111,7 @@ class ResourceMemberService {
 
 			return $member;
 		} catch (Exception $e) {
-			$this->handleException($e);
+			$this->handleException($e, $id);
 		}
 	}
 }
\ No newline at end of file