diff --git a/src/Controllers/group.controllers.ts b/src/Controllers/group.controllers.ts
index 012e6f8..eaea779 100644
--- a/src/Controllers/group.controllers.ts
+++ b/src/Controllers/group.controllers.ts
@@ -6,11 +6,13 @@ import prisma from "../lib/prisma";
 import NotFoundError from "../Middleware/error/NotFoundError";
 import { createInsufficientPermissionsError, DataType, generateError, generateInvalidBodyError, genericError, handleCreateByName } from "./common";
 
-const updateGroupBody = z.object({
-  name: z.string(),
-  user_limit: z.number(),
-  level: z.number(),
-}).partial();
+const updateGroupBody = z
+  .object({
+    name: z.string().min(1),
+    user_limit: z.number().int().positive(),
+    level: z.number().int().nonnegative(),
+  })
+  .partial();
 
 const basicGroup = {
   pid: true,
@@ -131,11 +133,14 @@ export const updateGroup = async (req: Request<{ pid: string }>, res: Response)
 
   if(result.success === false){
       return res.status(400).json(
-          generateInvalidBodyError({
-              name: DataType.STRING,
-              user_limit: DataType.NUMBER,
-              level: DataType.NUMBER,
-          })
+        generateInvalidBodyError(
+          {
+            name: DataType.STRING,
+            user_limit: DataType.NUMBER,
+            level: DataType.NUMBER,
+          },
+          result.error
+        )
       );
   }
 
@@ -153,39 +158,17 @@ export const updateGroup = async (req: Request<{ pid: string }>, res: Response)
           select: basicGroup,
       });
   
-      if(!group) {
-          throw new NotFoundError("group", pid);
-      }
-  
       res.status(200).json({
           type: "success",
-          payload: group,
+          payload: { group },
       });
   
   } catch (e) {
-      if (e instanceof Prisma.PrismaClientKnownRequestError) {
-          return res.status(500).json({
-            type: "error",
-            payload: {
-              message: `Internal Server error occured. Try again later`,
-            },
-          });
-        }
-        if (e instanceof Prisma.PrismaClientUnknownRequestError) {
-          return res.status(500).json({
-            type: "error",
-            payload: {
-              message: "Unknown error occurred with your request. Check if your parameters are correct",
-              schema: {
-                name: DataType.STRING,
-                user_limit: DataType.NUMBER,
-                level: DataType.NUMBER,
-              },
-            },
-          });
-        }
+      if (e instanceof Prisma.PrismaClientKnownRequestError && e.code === "P2025") {
+          throw new NotFoundError("group", pid)
+      }
     
-        throw e;
+      throw e;
   }
 }
 
@@ -206,7 +189,7 @@ export const deleteGroup = async (req: Request<DeleteGroupQueryParams>, res: Res
     return res.status(204).end();
   } catch (e) {
     if (e instanceof PrismaClientKnownRequestError && e.code === "P2025") {
-      return res.status(404).json(generateError(`The group with the ID ${pid} could not be found`));
+      throw new NotFoundError("group", pid)
     }
 
     throw e;
diff --git a/src/Controllers/participant.controller.ts b/src/Controllers/participant.controller.ts
index d5696d1..8a1bb55 100644
--- a/src/Controllers/participant.controller.ts
+++ b/src/Controllers/participant.controller.ts
@@ -8,10 +8,13 @@ import NotFoundError from "../Middleware/error/NotFoundError";
 
 //TODO: add TeamleaderAuthentification
 
+// REVIEW: All this code should be able to be executed by the teamleader of the team the participant is in AND
+//         an admin the group of whom overlaps with the team AND an elevated admin
+
 const ParticipantBody = z.object({
     firstName: z.string(),
     lastName: z.string(),
-    groupId: z.string(),
+    groupId: z.string().uuid(),
     //job: z.enum(["TEAMLEADER", "MEMBER"]),
 });
 
@@ -30,6 +33,7 @@ const returnedParticipant = {
     } },
 } as const;
 
+// REVIEW: Location of this endpoints (/groups, /teams, /participants, ...?)
 export const createParticipant = async (req: Request<{ pid: string}>, res: Response) => {
     //insert TeamleaderAuth
 
@@ -41,7 +45,7 @@ export const createParticipant = async (req: Request<{ pid: string}>, res: Respo
                 firstname: DataType.STRING,
                 lastName: DataType.STRING,
                 groupId: DataType.UUID,
-            })
+            }, result.error)
         );
     }
 
@@ -62,7 +66,7 @@ export const createParticipant = async (req: Request<{ pid: string}>, res: Respo
 
         return res.status(201).json({
             type: "success",
-            payload: participant,
+            payload: { participant },
         });
     } catch (e) {
         if (e instanceof PrismaClientKnownRequestError && e.code === "P2025") {
@@ -75,7 +79,7 @@ export const createParticipant = async (req: Request<{ pid: string}>, res: Respo
 export const updateParticipant = async (req: Request<{ pid: string }>, res: Response) => {
     //insert TeamleaderAuth
 
-    const result = ParticipantBody.safeParse(req.body);
+    const result = ParticipantBody.partial().safeParse(req.body); // Should be partial, right?
 
     if(result.success === false){
         return res.status(400).json(
@@ -83,7 +87,7 @@ export const updateParticipant = async (req: Request<{ pid: string }>, res: Resp
                 firstname: DataType.STRING,
                 lastName: DataType.STRING,
                 groupId: DataType.UUID,
-            })
+            }, result.error)
         );
     }
 
@@ -101,38 +105,16 @@ export const updateParticipant = async (req: Request<{ pid: string }>, res: Resp
             select: returnedParticipant,
         });
     
-        if(!participant) {
-            throw new NotFoundError("participant", pid);
-        }
-    
         res.status(200).json({
             type: "success",
-            payload: participant,
+            payload: { participant },
         });
     
     } catch (e) {
-        if (e instanceof Prisma.PrismaClientKnownRequestError) {
-            return res.status(500).json({
-              type: "error",
-              payload: {
-                message: `Internal Server error occured. Try again later`,
-              },
-            });
+        if (e instanceof Prisma.PrismaClientKnownRequestError && e.code === "P2025") {
+            throw new NotFoundError("participant", pid)
           }
-          if (e instanceof Prisma.PrismaClientUnknownRequestError) {
-            return res.status(500).json({
-              type: "error",
-              payload: {
-                message: "Unknown error occurred with your request. Check if your parameters are correct",
-                schema: {
-                    firstname: DataType.STRING,
-                    lastName: DataType.STRING,
-                    groupId: DataType.UUID,
-                },
-              },
-            });
-          }
-      
+                
           throw e;
     }
 }