Most backend issues are generated by the misconfiguration of the Firestore Security Rules. These backed issues may include Grey Screen errors, Infinite Loading screen, Firestore record creating error, Data mismatch errors, etc.

And to solve these issues, the Firestore rules have to be updated, for which you can follow the given series of steps:

From within your FlutterFlow project, select Firestore > Settings > Scroll down to Firestore Rules > select Deploy/Redploy.

The next step is to see if the Firestore Rules and Indexes are Out of Date or Not Deployed (as shown in the image below). If yes, please click on the blue Deploy button to push the latest rules.

After clicking on the Deploy button, a confirmation dialog would be shown, highlighting the changes in the rules that are being made from the deployment.

This compares the existing rules in Firestore and highlights what changes are being made in the Firestore rules. These changes are required when a new collection is created or is been edited or if the rules are Out of Date.

You can review the changes, and then you can click on the Deploy Now button. An orange loading indicator would be shown, which means that the rules are getting deployed (This step usually finishes within less than a minute, and the loading indicator is replaced with a Green Checkbox button).

After completing this step, validate the Firestore schema by clicking on the blue Validate button. This ensures that everything is configured correctly and the Firestore collection schema matches with the Collection schema configured in FlutterFlow.