A daily SQL Server backup completes with: "Backup completed with warnings".
When checking the job log no warning can be found.
The message "Backup completed with warnings" doesn't have any context or details.
Bug 30982 has been opened to investigate possible scenarios where some warnings messages are prevented from being output to the log database.
There are specific scenarios that may cause this issue whereby a database may not be accessible in SQL Server.
Another scenario is where the backup selection tree in NVBU contains an entry for a database where it is seen as present but not selected and not crossed.
Code improvements will be introduce to handle these rare scenarios in a future version of Plug-in for SQL Server.
When a SQL Server backup completes with warning but no warning messages can be seen in the job log, compare the Backup Selection set with the items available for restore in the saveset produced.
If a database is missing, check the status of that particular database in SQL Server Management Studio and look for any error regarding that database.
Edit the Backup Selection set making sure all databases are selected correctly and save it again.
Once all databases are accessible and the selection set is correct, the warnings should disappear.
A future version of Plug-in for SQL Server will introduce better handling of the above scenarios.