gcloud app deploy error --> ERROR: (gcloud.app.deploy) Error Response: [13] An internal error occurred

I am new on gcloud apps, need help on deployment web apps.

I created an App Engine and a Cloud SQL for MYSQL, it is in a different project. Let's call App Engine as web1 and sql as mysql1.

When I deployed web1 using "gcloud app deploy app.yaml", the upload process was success but when in the process "Updating service" it turns with error "ERROR: (gcloud.app.deploy) Error Response: [13] An internal error occurred"

Here is with the full error

Updating service [default]...⠶DEBUG: Operation [apps/and-web-test/operations/f7c36da5-de76-436d-9e71-785d549273e0] complete. Result: {

"metadata": { "target": "apps/and-web-test/services/default/versions/and-web-mm-001", "method": "google.appengine.v1.Versions.CreateVersion", "user": "[email protected]", "insertTime": "2019-07-25T04:54:53.630Z", "endTime": "2019-07-25T04:55:11.386Z", "@type": "type.googleapis.com/google.appengine.v1.OperationMetadataV1" }, "done": true, "name": "apps/and-web-test/operations/f7c36da5-de76-436d-9e71-785d549273e0", "error": { "message": "An internal error occurred.", "code": 13 } } 

Is it because my script has a bug or something else that i need to setup like permission on the Cloud SQL project?