diff --git a/backend/src/app.ts b/backend/src/app.ts
index 0c5e8892..3ee7307b 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -9,6 +9,7 @@ import { EnvVars, getNumericEnvVar } from './util/envvars.js';
 import apiRouter from './routes/router.js';
 import swaggerMiddleware from './swagger.js';
 import swaggerUi from 'swagger-ui-express';
+import {errorHandler} from "./middleware/error-handling/error-handler";
 
 const logger: Logger = getLogger();
 
@@ -26,6 +27,8 @@ app.use('/api', apiRouter);
 // Swagger
 app.use('/api-docs', swaggerUi.serve, swaggerMiddleware);
 
+app.use(errorHandler);
+
 async function startServer() {
     await initORM();
 
diff --git a/backend/src/controllers/learning-objects.ts b/backend/src/controllers/learning-objects.ts
index e9d0d727..8f5b18b9 100644
--- a/backend/src/controllers/learning-objects.ts
+++ b/backend/src/controllers/learning-objects.ts
@@ -4,9 +4,9 @@ import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifie
 import learningObjectService from '../services/learning-objects/learning-object-service.js';
 import { EnvVars, getEnvVar } from '../util/envvars.js';
 import { Language } from '../entities/content/language.js';
-import { BadRequestException } from '../exceptions.js';
 import attachmentService from '../services/learning-objects/attachment-service.js';
 import { NotFoundError } from '@mikro-orm/core';
+import {BadRequestException} from "../exceptions/badRequestException";
 
 function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifier {
     if (!req.params.hruid) {
diff --git a/backend/src/controllers/learning-paths.ts b/backend/src/controllers/learning-paths.ts
index 37f92d91..bf6f94d7 100644
--- a/backend/src/controllers/learning-paths.ts
+++ b/backend/src/controllers/learning-paths.ts
@@ -2,13 +2,14 @@ import { Request, Response } from 'express';
 import { themes } from '../data/themes.js';
 import { FALLBACK_LANG } from '../config.js';
 import learningPathService from '../services/learning-paths/learning-path-service.js';
-import { BadRequestException, NotFoundException } from '../exceptions.js';
 import { Language } from '../entities/content/language.js';
 import {
     PersonalizationTarget,
     personalizedForGroup,
     personalizedForStudent,
 } from '../services/learning-paths/learning-path-personalization-util.js';
+import {BadRequestException} from "../exceptions/badRequestException";
+import {NotFoundException} from "../exceptions/not-found-exception";
 
 /**
  * Fetch learning paths based on query parameters.
diff --git a/backend/src/exceptions.ts b/backend/src/exceptions.ts
deleted file mode 100644
index e93a6c93..00000000
--- a/backend/src/exceptions.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-/**
- * Exception for HTTP 400 Bad Request
- */
-export class BadRequestException extends Error {
-    public status = 400;
-
-    constructor(error: string) {
-        super(error);
-    }
-}
-
-/**
- * Exception for HTTP 401 Unauthorized
- */
-export class UnauthorizedException extends Error {
-    status = 401;
-    constructor(message: string = 'Unauthorized') {
-        super(message);
-    }
-}
-
-/**
- * Exception for HTTP 403 Forbidden
- */
-export class ForbiddenException extends Error {
-    status = 403;
-
-    constructor(message: string = 'Forbidden') {
-        super(message);
-    }
-}
-
-/**
- * Exception for HTTP 404 Not Found
- */
-export class NotFoundException extends Error {
-    public status = 404;
-
-    constructor(error: string) {
-        super(error);
-    }
-}
diff --git a/backend/src/exceptions/bad-request-exception.ts b/backend/src/exceptions/bad-request-exception.ts
new file mode 100644
index 00000000..eb5d4db0
--- /dev/null
+++ b/backend/src/exceptions/bad-request-exception.ts
@@ -0,0 +1,10 @@
+import {ExceptionWithHttpState} from "./exception-with-http-state.js";
+
+/**
+ * Exception for HTTP 400 Bad Request
+ */
+export abstract class BadRequestException extends ExceptionWithHttpState {
+    constructor(error: string) {
+        super(400, error);
+    }
+}
diff --git a/backend/src/exceptions/conflict-exception.ts b/backend/src/exceptions/conflict-exception.ts
new file mode 100644
index 00000000..b69081cb
--- /dev/null
+++ b/backend/src/exceptions/conflict-exception.ts
@@ -0,0 +1,12 @@
+import {ExceptionWithHttpState} from "./exception-with-http-state.js";
+
+/**
+ * Exception for HTTP 409 Conflict
+ */
+export class ConflictException extends ExceptionWithHttpState {
+    public status = 409;
+
+    constructor(error: string) {
+        super(409, error);
+    }
+}
diff --git a/backend/src/exceptions/exception-with-http-state.ts b/backend/src/exceptions/exception-with-http-state.ts
new file mode 100644
index 00000000..fab6b1dd
--- /dev/null
+++ b/backend/src/exceptions/exception-with-http-state.ts
@@ -0,0 +1,9 @@
+/**
+ * Exceptions which are associated with a HTTP error code.
+ */
+export abstract class ExceptionWithHttpState extends Error {
+    constructor(public status: number, public error: string) {
+        super(error);
+    }
+}
+
diff --git a/backend/src/exceptions/forbidden-exception.ts b/backend/src/exceptions/forbidden-exception.ts
new file mode 100644
index 00000000..ba084162
--- /dev/null
+++ b/backend/src/exceptions/forbidden-exception.ts
@@ -0,0 +1,12 @@
+import {ExceptionWithHttpState} from "./exception-with-http-state.js";
+
+/**
+ * Exception for HTTP 403 Forbidden
+ */
+export class ForbiddenException extends ExceptionWithHttpState {
+    status = 403;
+
+    constructor(message: string = 'Forbidden') {
+        super(403, message);
+    }
+}
diff --git a/backend/src/exceptions/not-found-exception.ts b/backend/src/exceptions/not-found-exception.ts
new file mode 100644
index 00000000..8fb2f3f1
--- /dev/null
+++ b/backend/src/exceptions/not-found-exception.ts
@@ -0,0 +1,12 @@
+import {ExceptionWithHttpState} from "./exception-with-http-state.js";
+
+/**
+ * Exception for HTTP 404 Not Found
+ */
+export class NotFoundException extends ExceptionWithHttpState {
+    public status = 404;
+
+    constructor(error: string) {
+        super(404, error);
+    }
+}
diff --git a/backend/src/exceptions/unauthorized-exception.ts b/backend/src/exceptions/unauthorized-exception.ts
new file mode 100644
index 00000000..1c61a742
--- /dev/null
+++ b/backend/src/exceptions/unauthorized-exception.ts
@@ -0,0 +1,10 @@
+import {ExceptionWithHttpState} from "./exception-with-http-state.js";
+
+/**
+ * Exception for HTTP 401 Unauthorized
+ */
+export class UnauthorizedException extends ExceptionWithHttpState {
+    constructor(message: string = 'Unauthorized') {
+        super(401, message);
+    }
+}
diff --git a/backend/src/middleware/auth/auth.ts b/backend/src/middleware/auth/auth.ts
index 5ff5a53c..b98fb262 100644
--- a/backend/src/middleware/auth/auth.ts
+++ b/backend/src/middleware/auth/auth.ts
@@ -6,7 +6,8 @@ import * as express from 'express';
 import * as jwt from 'jsonwebtoken';
 import { AuthenticatedRequest } from './authenticated-request.js';
 import { AuthenticationInfo } from './authentication-info.js';
-import { ForbiddenException, UnauthorizedException } from '../../exceptions.js';
+import {UnauthorizedException} from "../../exceptions/unauthorized-exception";
+import {ForbiddenException} from "../../exceptions/forbidden-exception";
 
 const JWKS_CACHE = true;
 const JWKS_RATE_LIMIT = true;
diff --git a/backend/src/middleware/error-handling/error-handler.ts b/backend/src/middleware/error-handling/error-handler.ts
new file mode 100644
index 00000000..0c91f511
--- /dev/null
+++ b/backend/src/middleware/error-handling/error-handler.ts
@@ -0,0 +1,15 @@
+import {NextFunction, Request, Response} from "express";
+import {getLogger, Logger} from "../../logging/initalize";
+import {ExceptionWithHttpState} from "../../exceptions/exception-with-http-state";
+
+const logger: Logger = getLogger();
+
+export function errorHandler(err: unknown, req: Request, res: Response, _: NextFunction): void {
+    if (err instanceof ExceptionWithHttpState) {
+        logger.warn(`An error occurred while handling request ${JSON.stringify(req)}: ${err.error} (-> HTTP ${err.status})`);
+        res.status(err.status).json(err);
+    } else {
+        logger.error(`Unexpected error occurred while handling request ${JSON.stringify(req)}: ${JSON.stringify(err)}`);
+        res.status(500).json(err);
+    }
+}
diff --git a/backend/src/services/students.ts b/backend/src/services/students.ts
index 97e41427..da73f8ad 100644
--- a/backend/src/services/students.ts
+++ b/backend/src/services/students.ts
@@ -5,6 +5,9 @@ import { GroupDTO, mapToGroupDTO, mapToGroupDTOId } from '../interfaces/group.js
 import { mapToStudent, mapToStudentDTO, StudentDTO } from '../interfaces/student.js';
 import { mapToSubmissionDTO, mapToSubmissionDTOId, SubmissionDTO, SubmissionDTOId } from '../interfaces/submission.js';
 import { getAllAssignments } from './assignments.js';
+import {UniqueConstraintViolationException} from "@mikro-orm/core";
+
+import {ConflictException} from "../exceptions/conflict-exception";
 
 export async function getAllStudents(full: boolean): Promise<StudentDTO[] | string[]> {
     const studentRepository = getStudentRepository();
@@ -29,11 +32,12 @@ export async function createStudent(userData: StudentDTO): Promise<StudentDTO |
     try {
         const newStudent = mapToStudent(userData);
         await studentRepository.save(newStudent);
-
         return mapToStudentDTO(newStudent);
-    } catch (e) {
-        console.log(e);
-        return null;
+    } catch (e: unknown) {
+        if (e instanceof UniqueConstraintViolationException) {
+            throw new ConflictException(`There is already a user with username '${userData.username}'.`);
+        }
+        throw e;
     }
 }
 
diff --git a/backend/src/services/teachers.ts b/backend/src/services/teachers.ts
index 77cea501..1f5caa25 100644
--- a/backend/src/services/teachers.ts
+++ b/backend/src/services/teachers.ts
@@ -2,17 +2,16 @@ import {
     getClassRepository,
     getLearningObjectRepository,
     getQuestionRepository,
-    getStudentRepository,
     getTeacherRepository,
 } from '../data/repositories.js';
-import { Teacher } from '../entities/users/teacher.entity.js';
 import { ClassDTO, mapToClassDTO } from '../interfaces/class.js';
 import { getClassStudents } from './classes.js';
 import { StudentDTO } from '../interfaces/student.js';
 import { mapToQuestionDTO, mapToQuestionId, QuestionDTO, QuestionId } from '../interfaces/question.js';
-import { mapToUser } from '../interfaces/user.js';
 import { mapToTeacher, mapToTeacherDTO, TeacherDTO } from '../interfaces/teacher.js';
-import { teachersOnly } from '../middleware/auth/auth.js';
+import {UniqueConstraintViolationException} from "@mikro-orm/core";
+
+import {ConflictException} from "../exceptions/conflict-exception";
 
 export async function getAllTeachers(full: boolean): Promise<TeacherDTO[] | string[]> {
     const teacherRepository = getTeacherRepository();
@@ -40,8 +39,10 @@ export async function createTeacher(userData: TeacherDTO): Promise<TeacherDTO |
 
         return mapToTeacherDTO(newTeacher);
     } catch (e) {
-        console.log(e);
-        return null;
+        if (e instanceof UniqueConstraintViolationException) {
+            throw new ConflictException(`There is already a user with username '${userData.username}'.`);
+        }
+        throw e;
     }
 }