Azure App Service Backup Failing with Generic Error

Question

I have a Web Site and Azure SQL database. In the App Service under Settings->Backup I have it configured to backup daily the site and database. For 2 years it worked fine, on April 1, 2021 the backup started failing with the following error: "Object reference not set to an instance of an object." The site as well as database are operating without issue. There have been no recent updates to either the site or database and the database size and site are under the 10g limit. I reset the Backup Configuration and create a new one but the same error resulted.

Answer 1

Update: This is now resolved. Here the issue was the DB was about 30gb but limit is 4.
As documented here: https://learn.microsoft.com/en-us/azure/app-service/manage-backup#configure-partial-backups
After removing the database from the backup, the app service backed up as expected. 

Helpful document links:

SQL Automatic Backups: https://learn.microsoft.com/en-us/azure/azure-sql/database/automated-backups-overview?tabs=single-database

BACPAC files: https://learn.microsoft.com/en-us/sql/relational-databases/data-tier-applications/data-tier-applications?view=sql-server-ver15#bacpac

Exporting BACPAC: https://learn.microsoft.com/en-us/azure/azure-sql/database/database-export?WT.mc_id=Portal-Microsoft_Azure_Support#export-to-a-bacpac-file-using-the-sqlpackage-utility