Firebase functions deploy 403 Permission denied on 'locations/null' error - firebase

Question

I am trying to deploy Firebase functions project, on two different target projects on Firebase. One is in region "us-cenral" and the other one is "europe-west".
I'm using only functions and RTDB from Firebase, I don't have a need for "hosting".
At the start, I was having only one Firebase project region:"us-central" and I was able to deploy functions without problem. I have created another project recently in region:"europe-west" on the same billing account. And also in the local project I have added that another project using command:
firebase use --add project2
Since I didn't deploy functions for a couple of months and there was no need to check if deployment is still working on "project1" I have not checked if this functionally is working.
After adding "project2" I have issued command to deploy for the first time on another region.
When using command: "firebase deploy --only functions"
command ended with the following error:
There was an issue deploying your functions. Verify that your project has a Google App Engine instance setup at https://console.cloud.google.com/appengine and try again. If this issue persists, please contact support.
! functions: Upload Error: HTTP Error: 403, Permission denied on 'locations/null' (or it may not exist).
Error: HTTP Error: 403, Permission denied on 'locations/null' (or it may not exist).
[2022-05-11T19:32:17.580Z] Error Context: {
"body": {
"error": {
"code": 403,
"message": "Permission denied on 'locations/null' (or it may not exist).",
"status": "PERMISSION_DENIED"
}
},
"response": {
"statusCode": 403
}
}
Switching back to project1 and trying to deploy the same thing, I got the same error.
So now I'm stuck. Does anyone have experience with this problem and how to overcome it.
Google support suggest to create "App Engine application", I cannot see how this can help as I didn't had that thing in the 1st place and everything was working. Now with the second project I have this error that suggest permissions problem. Since I have OWNER account on both of these projects what could be wrong?
What I have done so far:
installed the latest firebase tools (same problem)
defined default region on both projects (as stated above)
checked that I'm logged with the OWNER account (also switched between different owner account but the same issue)
checked permissions and din't find anything useful
default service accounts exist on both projects with rights
visited suggested link: https://console.cloud.google.com/appengine
on both projects (and still have the same error although not sure if I need to deploy?!? - I don't have anything there to deploy or do I?)
Config package.json:
{
"name": "functions",
"description": "Cloud Functions for Firebase",
"engines": {
"node": "10"
},
"dependencies": {
"canvas": "^2.6.1",
"firebase-admin": "^10.2.0",
"firebase-functions": "^3.21.0",
"jsbarcode": "^3.11.0",
"qrcode": "^1.4.4"
},
"devDependencies": {
"eslint": "^5.16.0",
"eslint-plugin-promise": "^4.0.1",
"firebase-functions-test": "^0.2.0"
},
"private": true
}
Configuration didn't changed from the 1st deploy to project1 when everything was working fine.

Answer 1

At the end I found out the reason for my problem, and posting just to help the others if they end up with the same error.
The problem was not deployment script "per se" but the function that was connected to fetch data from RTDB on the project. Method "region" was supposed to get configured "region(fnRegion)" value, but that variable value was "null" and resulted with the error posted above during deployment.
function selectDatabaseReference(path = '/') {
return functions
.region(fnRegion) // Sets function region
.database
.ref(path); // Sets database reference path
}
It would be nice if I could get more descriptive error to the real cause of the error (I'm not truly sure, what would be the content of that error message though).
Anyway it's good I was not able to deploy functions because of this.