Getting unable to open database file error in Django sqlite3

Tried deploying my Python Django application to fly.io and ran into these problems. I created the volume and mentioned that in my toml.file like these.

[mounts]
  destination = "/mnt/myappdb"
  source = "myappdb"

And also I have set environment variable correctly…

 flyctl secrets set DATABASE_URL=sqlite://mnt/myappdb/production.sqlite

The error happening on the release command.

[deploy]
  release_command = "python manage.py migrate"

I also tried running above command in the console and same problem happening. Seeing other thread similar to this one not helping. I don’t know how to set the permission either.

Anyone know the solution to this? I believe it’s something to do with the permission and I can’t able to set it properly.