Please clarify what backup solution you are referring to? Veeam Agent for Windows or Veeam Backup&Replication? Any chance you have a support case ID? Thanks in advance.
Reset the database information so that it recognizes the new disk ID from Windows.
To do so without clearing up the database, set the backup job to run a file level backup, adding files that are on an active volume. Run the backup job immediately afterwards. If the job runs successfully, this should mean that the disk ID information has been re-added to the database. It should be safe to change the backup configuration to a volume level backup.
Reset the database information so that it recognizes the new disk ID from Windows.
To do so without clearing up the database, set the backup job to run a file level backup, adding files that are on an active volume. Run the backup job immediately afterwards. If the job runs successfully, this should mean that the disk ID information has been re-added to the database. It should be safe to change the backup configuration to a volume level backup.
Yes, Veeam Agent for Windows is supported and no, it's not retired (latest version of the product). If the issue is not resolved and you still have that error, please open a case (it’s free) via Control Panel > Support > Technical Support. It may require email address registration, so make sure confirmation email was not moved to Junk folder.