diff --git a/apps/backend/controllers/djs.controller.ts b/apps/backend/controllers/djs.controller.ts
index 1e160cf..72ad915 100644
--- a/apps/backend/controllers/djs.controller.ts
+++ b/apps/backend/controllers/djs.controller.ts
@@ -12,7 +12,7 @@ export type binBody = {
 export const addToBin: RequestHandler<object, unknown, binBody> = async (req, res, next) => {
   if (req.body.album_id === undefined || req.body.dj_id === undefined) {
     console.error('Bad Request, Missing Album Identifier: album_id');
-    res.status(400).send('Bad Request, Missing DJ or album identifier: album_id');
+    res.status(400).json({ message: 'Bad Request, Missing DJ or album identifier: album_id' });
   } else {
     const bin_entry: NewBinEntry = {
       dj_id: req.body.dj_id,
@@ -40,7 +40,7 @@ export type binQuery = {
 export const deleteFromBin: RequestHandler<object, unknown, unknown, binQuery> = async (req, res, next) => {
   if (req.query.album_id === undefined || req.query.dj_id === undefined) {
     console.error('Bad Request, Missing Bin Entry Identifier: album_id or dj_id');
-    res.status(400).send('Bad Request, Missing Bin Entry Identifier: album_id or dj_id');
+    res.status(400).json({ message: 'Bad Request, Missing Bin Entry Identifier: album_id or dj_id' });
   } else {
     try {
       //check that the dj_id === dj_id of bin entry
@@ -56,7 +56,7 @@ export const deleteFromBin: RequestHandler<object, unknown, unknown, binQuery> =
 export const getBin: RequestHandler<object, unknown, object, { dj_id: string }> = async (req, res, next) => {
   if (req.query.dj_id === undefined) {
     console.error('Bad Request, Missing DJ Identifier: dj_id');
-    res.status(400).send('Bad Request, Missing DJ Identifier: dj_id');
+    res.status(400).json({ message: 'Bad Request, Missing DJ Identifier: dj_id' });
   } else {
     try {
       const dj_bin = await DJService.getBinFromDB(req.query.dj_id);
@@ -72,7 +72,7 @@ export const getBin: RequestHandler<object, unknown, object, { dj_id: string }>
 export const getPlaylistsForDJ: RequestHandler<object, unknown, object, { dj_id: string }> = async (req, res, next) => {
   if (req.query.dj_id === undefined) {
     console.error('Bad Request, Missing DJ Identifier: dj_id');
-    res.status(400).send('Bad Request, Missing DJ Identifier: dj_id');
+    res.status(400).json({ message: 'Bad Request, Missing DJ Identifier: dj_id' });
   } else {
     try {
       const playlists = await DJService.getPlaylistsForDJ(req.query.dj_id);
@@ -88,7 +88,7 @@ export const getPlaylistsForDJ: RequestHandler<object, unknown, object, { dj_id:
 export const getPlaylist: RequestHandler<object, unknown, object, { playlist_id: string }> = async (req, res, next) => {
   if (req.query.playlist_id === undefined) {
     console.error('Bad Request, Missing Playlist Identifier: playlist_id');
-    res.status(400).send('Bad Request, Missing Playlist Identifier: playlist_id');
+    res.status(400).json({ message: 'Bad Request, Missing Playlist Identifier: playlist_id' });
   } else {
     try {
       const playlist = await DJService.getPlaylist(parseInt(req.query.playlist_id));
diff --git a/apps/backend/controllers/flowsheet.controller.ts b/apps/backend/controllers/flowsheet.controller.ts
index c8074c5..c4d056a 100644
--- a/apps/backend/controllers/flowsheet.controller.ts
+++ b/apps/backend/controllers/flowsheet.controller.ts
@@ -109,7 +109,7 @@ export const getLatest: RequestHandler = async (req, res, next) => {
       res.status(200).json(latest[0]);
     } else {
       console.error('No Tracks found');
-      res.status(404).send('Error: No Tracks found');
+      res.status(404).json({ message: 'No Tracks found' });
     }
   } catch (e) {
     console.error('Error: Failed to retrieve track');
@@ -142,13 +142,13 @@ export const addEntry: RequestHandler = async (req: Request<object, object, FSEn
   }
   if (latestShow?.end_time !== null) {
     console.error('Bad Request, There are no active shows');
-    res.status(400).send('Bad Request, There are no active shows');
+    res.status(400).json({ message: 'Bad Request, There are no active shows' });
   } else {
     if (body.message === undefined) {
       // no message passed, so we assume we're adding a track to the flowsheet
       if (body.track_title === undefined) {
         console.error('Bad Request, Missing query parameter: track_title');
-        res.status(400).send('Bad Request, Missing query parameter: track_title');
+        res.status(400).json({ message: 'Bad Request, Missing query parameter: track_title' });
       } else {
         try {
           if (body.album_id !== undefined) {
@@ -189,7 +189,9 @@ export const addEntry: RequestHandler = async (req: Request<object, object, FSEn
             body.track_title === undefined
           ) {
             console.error('Bad Request, Missing Flowsheet Parameters: album_title, artist_name, track_title');
-            res.status(400).send('Bad Request, Missing Flowsheet Parameters: album_title, artist_name, track_title');
+            res
+              .status(400)
+              .json({ message: 'Bad Request, Missing Flowsheet Parameters: album_title, artist_name, track_title' });
           } else {
             const fsEntry: NewFSEntry = {
               ...body,
@@ -243,7 +245,7 @@ export const deleteEntry: RequestHandler<object, unknown, { entry_id: number }>
   const { entry_id } = req.body;
   if (entry_id === undefined) {
     console.error('Bad Request, Missing entry identifier: entry_id');
-    res.status(400).send('Bad Request, Missing entry identifier: entry_id');
+    res.status(400).json({ message: 'Bad Request, Missing entry identifier: entry_id' });
   } else {
     try {
       const removedEntry: FSEntry = await flowsheet_service.removeTrack(entry_id);
@@ -273,7 +275,7 @@ export const updateEntry: RequestHandler<object, unknown, { entry_id: number; da
   const { entry_id, data } = req.body;
   if (entry_id === undefined) {
     console.error('Bad Request, Missing entry identifier: entry_id');
-    res.status(400).send('Bad Request, Missing entry identifier: entry_id');
+    res.status(400).json({ message: 'Bad Request, Missing entry identifier: entry_id' });
   } else {
     try {
       const updatedEntry: FSEntry = await flowsheet_service.updateEntry(entry_id, data);
@@ -296,7 +298,7 @@ export type JoinRequestBody = {
 export const joinShow: RequestHandler = async (req: Request<object, object, JoinRequestBody>, res, next) => {
   const current_show = await flowsheet_service.getLatestShow();
   if (req.body.dj_id === undefined) {
-    res.status(400).send('Bad Request, Must include a dj_id to join show');
+    res.status(400).json({ message: 'Bad Request, Must include a dj_id to join show' });
   } else if (current_show?.end_time !== null) {
     try {
       const show_session: Show = await flowsheet_service.startShow(
@@ -416,7 +418,7 @@ export const getShowInfo: RequestHandler<object, unknown, object, { show_id: str
   const showId = parseInt(req.query.show_id);
   if (isNaN(showId)) {
     console.error('Bad Request, Missing Show Identifier: show_id');
-    res.status(400).send('Bad Request, Missing Show Identifier: show_id');
+    res.status(400).json({ message: 'Bad Request, Missing Show Identifier: show_id' });
   } else {
     try {
       const showInfo = await flowsheet_service.getPlaylist(showId);
diff --git a/apps/backend/controllers/library.controller.ts b/apps/backend/controllers/library.controller.ts
index 2210e03..7a75ba6 100644
--- a/apps/backend/controllers/library.controller.ts
+++ b/apps/backend/controllers/library.controller.ts
@@ -34,7 +34,6 @@ export const addAlbum: RequestHandler = async (req: Request<object, object, NewA
     (body.artist_name === undefined && body.artist_id === undefined)
   ) {
     res.status(400).json({
-      status: 400,
       message: 'Missing Parameters: album_title, label, genre_id, format_id, artist_name, or artist_id',
     });
   } else {
@@ -49,10 +48,10 @@ export const addAlbum: RequestHandler = async (req: Request<object, object, NewA
       }
     }
     if (!artist_id) {
-      res.status(400);
-      res.send(
-        "Artist doesn't exist or hasn't released an album in this genre before. Add a new artist entry to the library"
-      );
+      res.status(400).json({
+        message:
+          "Artist doesn't exist or hasn't released an album in this genre before. Add a new artist entry to the library",
+      });
     } else {
       try {
         const new_album: NewAlbum = {
@@ -98,14 +97,13 @@ export const searchForAlbum: RequestHandler = async (
     query.album_title === undefined &&
     (query.code_letters === undefined || query.code_artist_number === undefined)
   ) {
-    res.status(400);
-    res.send(
-      'Missing query parameter. Query must include: artist_name, album_title, or code_letters, code_artist_number, and code_number'
-    );
+    res.status(400).json({
+      message:
+        'Missing query parameter. Query must include: artist_name, album_title, or code_letters, code_artist_number, and code_number',
+    });
   } else if (query.code_letters !== undefined && query.code_artist_number !== undefined) {
     //quickly look up albums by that artist
-    res.status(501);
-    res.send('TODO: Library Code Lookup');
+    res.status(501).json({ message: 'TODO: Library Code Lookup' });
   } else {
     try {
       const response = await libraryService.fuzzySearchLibrary(query.artist_name, query.album_title, query.n);
@@ -128,8 +126,7 @@ export const addArtist: RequestHandler = async (req: Request<object, object, New
   const { body } = req;
   //TODO auto_generate artist code letters and make it an optional parameter
   if (body.artist_name === undefined || body.code_letters === undefined || body.genre_id === undefined) {
-    res.status(400);
-    res.send('Missing Request Parameters: artist_name, code_letters, or genre_id');
+    res.status(400).json({ message: 'Missing Request Parameters: artist_name, code_letters, or genre_id' });
   } else {
     try {
       const generatedArtistNumber = await libraryService.generateArtistNumber(body.code_letters, body.genre_id);
@@ -166,7 +163,7 @@ export const getRotation: RequestHandler = async (req, res, next) => {
 export type RotationAddRequest = Omit<NewRotationRelease, 'id'>;
 export const addRotation: RequestHandler<object, unknown, NewRotationRelease> = async (req, res, next) => {
   if (req.body.album_id === undefined || req.body.rotation_bin === undefined) {
-    res.status(400).send('Missing Parameters: album_id or rotation_bin');
+    res.status(400).json({ message: 'Missing Parameters: album_id or rotation_bin' });
   } else {
     try {
       const rotationRelease: RotationRelease = await libraryService.addToRotation(req.body);
@@ -187,16 +184,16 @@ export const killRotation: RequestHandler<object, unknown, KillRotationRelease>
   const { body } = req;
 
   if (body.rotation_id === undefined) {
-    res.status(400).send('Bad Request, Missing Parameter: rotation_id');
+    res.status(400).json({ message: 'Bad Request, Missing Parameter: rotation_id' });
   } else if (body.kill_date !== undefined && !libraryService.isISODate(body.kill_date)) {
-    res.status(400).send('Bad Request, Incorrect Date Format: kill_date should be of form YYYY-MM-DD');
+    res.status(400).json({ message: 'Bad Request, Incorrect Date Format: kill_date should be of form YYYY-MM-DD' });
   } else {
     try {
       const updatedRotation: RotationRelease = await libraryService.killRotationInDB(body.rotation_id, body.kill_date);
       if (updatedRotation !== undefined) {
         res.status(200).json(updatedRotation);
       } else {
-        res.status(400).json({ status: 400, message: 'Rotation entry not found' });
+        res.status(400).json({ message: 'Rotation entry not found' });
       }
     } catch (e) {
       console.error('Failed to update rotation kill_date');
@@ -220,7 +217,7 @@ export const getFormats: RequestHandler = async (req, res, next) => {
 export const addFormat: RequestHandler = async (req, res, next) => {
   const { body } = req;
   if (body.name === undefined) {
-    res.status(400).send('Bad Request, Missing Parameter: name');
+    res.status(400).json({ message: 'Bad Request, Missing Parameter: name' });
   } else {
     try {
       const newFormat: NewAlbumFormat = {
@@ -245,7 +242,7 @@ export const getGenres: RequestHandler = async (req, res) => {
 export const addGenre: RequestHandler = async (req, res, next) => {
   const { body } = req;
   if (body.name === undefined || body.description === undefined) {
-    res.status(400).send('Bad Request, Parameters name and description are required.');
+    res.status(400).json({ message: 'Bad Request, Parameters name and description are required.' });
   } else {
     try {
       const newGenre: NewGenre = {
@@ -271,7 +268,7 @@ export const getAlbum: RequestHandler<object, unknown, unknown, { album_id: stri
   const { query } = req;
   if (query.album_id === undefined) {
     console.error('Bad Request, missing album identifier: album_id');
-    res.status(400).send('Bad Request, missing album identifier: album_id');
+    res.status(400).json({ message: 'Bad Request, missing album identifier: album_id' });
   } else {
     try {
       const album = await libraryService.getAlbumFromDB(parseInt(query.album_id));
diff --git a/apps/backend/middleware/errorHandler.ts b/apps/backend/middleware/errorHandler.ts
index e10636b..6b266b6 100644
--- a/apps/backend/middleware/errorHandler.ts
+++ b/apps/backend/middleware/errorHandler.ts
@@ -10,7 +10,8 @@ function errorHandler(err: any, req: Request, res: Response, next: NextFunction)
   if (error instanceof WxycError) {
     res.status(error.statusCode).json({ message: error.message });
   } else {
-    res.status(500).json({ message: error.message });
+    console.error('Unhandled error:', error);
+    res.status(500).json({ message: 'Internal server error' });
   }
 }
 
diff --git a/tests/unit/middleware/errorHandler.test.ts b/tests/unit/middleware/errorHandler.test.ts
new file mode 100644
index 0000000..01b566b
--- /dev/null
+++ b/tests/unit/middleware/errorHandler.test.ts
@@ -0,0 +1,58 @@
+import errorHandler from '../../../apps/backend/middleware/errorHandler';
+import WxycError from '../../../apps/backend/utils/error';
+import { Request, Response, NextFunction } from 'express';
+
+function mockResponse() {
+  const statusMock = jest.fn().mockReturnThis();
+  const jsonMock = jest.fn().mockReturnThis();
+  const res = {
+    status: statusMock,
+    json: jsonMock,
+  } as unknown as Response;
+  return { res, statusMock, jsonMock };
+}
+
+const mockReq = {} as Request;
+const mockNext = jest.fn() as NextFunction;
+
+describe('errorHandler middleware', () => {
+  it('returns { message } with correct status for WxycError', () => {
+    const { res, statusMock, jsonMock } = mockResponse();
+    const error = new WxycError('Album not found', 404);
+
+    errorHandler(error, mockReq, res, mockNext);
+
+    expect(statusMock).toHaveBeenCalledWith(404);
+    expect(jsonMock).toHaveBeenCalledWith({ message: 'Album not found' });
+  });
+
+  it('returns generic message for non-WxycError (does not leak internals)', () => {
+    const { res, statusMock, jsonMock } = mockResponse();
+    const error = new Error('SELECT * FROM users failed: connection refused');
+
+    errorHandler(error, mockReq, res, mockNext);
+
+    expect(statusMock).toHaveBeenCalledWith(500);
+    expect(jsonMock).toHaveBeenCalledWith({ message: 'Internal server error' });
+  });
+
+  it('handles non-Error values thrown', () => {
+    const { res, statusMock, jsonMock } = mockResponse();
+
+    errorHandler('something broke', mockReq, res, mockNext);
+
+    expect(statusMock).toHaveBeenCalledWith(500);
+    expect(jsonMock).toHaveBeenCalledWith({ message: 'Internal server error' });
+  });
+
+  it('logs non-WxycError errors to console', () => {
+    const { res } = mockResponse();
+    const error = new Error('db connection lost');
+    const consoleSpy = jest.spyOn(console, 'error').mockImplementation();
+
+    errorHandler(error, mockReq, res, mockNext);
+
+    expect(consoleSpy).toHaveBeenCalledWith('Unhandled error:', error);
+    consoleSpy.mockRestore();
+  });
+});