Update post.js

src/errors/ApiError.js

@@ -4,5 +4,7 @@ class ApiError {
     this.code = code;
   }
 }
-
+// Is this class doing anything besides receiving data? what is the return?
+// Take a look at this Method in the Erro object: Error.captureStackTrace(this);
+// Also, read this: https://stackoverflow.com/questions/59625425/understanding-error-capturestacktrace-and-stack-trace-persistance
 export default ApiError;

src/middlewares/handleErrors.js

@@ -2,6 +2,7 @@
 import ApiError from '../errors/ApiError';
 
 export default function ErrorHandler(error, req, res, next) {
+  //Ok, now I got why you created the de ApiError class. I thought you were going to throw the stack traces. You may "ignore" what I commented, but don't forget to read about it.
   if (error instanceof ApiError) {
     return res.status(error.code).send({
       error: {

src/routes/photos.routes.js

@@ -17,7 +17,9 @@ const upload = multer({
       || file.mimetype === 'image/jpeg'
     ) {
       cb(null, true);
+      // try to always avoid the use of "else" statement. In this case you can just return cb(null, true)
     } else {
+      // Why do you declare cb(null,false), and right after return it differently (as an ApiError instance)?
       cb(null, false);
       return cb(new ApiError(400, 'Only .png, .jpg and .jpeg format allowed!'));
     }

src/validation/post.js

@@ -1,5 +1,5 @@
 import Joi from '@hapi/joi';
-
+// Switch it 'npm install joi'
 const createPhoto = Joi.object({
   caption: Joi.string().min(1).max(266).trim()
     .required(),