Firebase Permission denied Error

It's because you are not authorized to the Database, check the Rules Tab in the Realtime database

If it's

{
  "rules": {
    ".read": "auth != null",
    ".write":"auth != null"
  }
}

This means only authorized user's can write and read the Data.

Changing to

{
  "rules": {
    ".read": true,
    ".write":true
  }
}

Allows anyone to write the Database

When going for Production be sure to use the first one

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