@firebase/database: FIREBASE WARNING: update at /users failed: permission_denied code example

Example: @firebase/database: FIREBASE WARNING: update at /users failed: permission_denied

Open firebase, select database on the left hand side.
Now on the right hand side, select [Realtime database] from the dropdown and change the rules to:
{
"rules": {
".read": true,
".write": true
}
}