Hi, I've solved that error, but can you help me with writing a code in the route I've posted in the problem, this is my schema: ratings: [ { user: { type: Schema.Types.ObjectId, ref: "users" }, ratingNumber: { type: Number } } ], and I want to sum al the ratingNumbers and divide by the number of the elements in the ratingNumber array.

Hi, I tried that and I don't get the POST error anymore but now I have this error in my terminal: (Nothing gets stored into db when I make rating action) "(node:8292) [DEP0079] DeprecationWarning: Custom inspection function on Objects via .inspect() is deprecated [0] (node:8292) UnhandledPromiseRejectionWarning: ValidationError: profile validation failed: subject: Path subject is required. [0] at new ValidationError node_modules\mongoose\lib\error\validation.js:30:11) [0] at model.Document.invalidate \node_modules\mongoose\lib\document.js:2085:32) [0] at p.doValidate.skipSchemaValidators \node_modules\mongoose\lib\document.js:1948:17) [0] at \node_modules\mongoose\lib\schematype.js:929:9 [0] at process._tickCallback (internal/process/next_tick.js:61:11) [0] (node:8292) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) [0] (node:8292) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code."