Obtengo lo siguiente cuando llamo a una ruta en mi proyecto:

 serveur running PORT: 7000 /user/new CastError: Cast to ObjectId failed for value "favicon.ico" (type string) at path "_id" for model "User" at model.Query.exec (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\query.js:4650:21) at model.Query.Query.then (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\query.js:4749:15) at exports.findOneUser (C:\Users\Admin\Downloads\books\routes\homeController.js:38:6) at Layer.handle [as handle_request] (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\layer.js:95:5) at next (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\route.js:137:13) at Route.dispatch (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\route.js:112:3) at Layer.handle [as handle_request] (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\layer.js:95:5) at C:\Users\Admin\Downloads\books\node_modules\express\lib\router\index.js:281:22 at param (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\index.js:360:14) at param (C:\Users\Admin\Downloads\books\node_modules\express\lib\router\index.js:371:14) { messageFormat: undefined, stringValue: '"favicon.ico"', kind: 'ObjectId', value: 'favicon.ico', path: '_id', reason: BSONTypeError: Argument passed in must be a string of 12 bytes or a string of 24 hex characters at new BSONTypeError (C:\Users\Admin\Downloads\books\node_modules\bson\lib\error.js:41:28) at new ObjectId (C:\Users\Admin\Downloads\books\node_modules\bson\lib\objectid.js:65:23) at castObjectId (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\cast\objectid.js:24:12) at ObjectId.cast (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\schema\objectid.js:247:12) at ObjectId.SchemaType.applySetters (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\schematype.js:1180:12) at ObjectId.SchemaType._castForQuery (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\schematype.js:1614:15) at ObjectId.SchemaType.castForQuery (C:\Users\Admin\Downloads\books\node_modules\mongoose\lib\schematype.js:1604:15)

Tengo una ruta (como route.get("/", myCallBack) ) que devuelve todos los objetos en mi base de datos mongodb. No puedo encontrar donde está mi error.