Recently I upgraded our Veeam install to 188.8.131.524 and began receiving this error on a bunch of our backups.
“Failed to finalize the guest processing. Details: Failed to process ‘TruncateSQLLog’ command. Failed to truncate transaction logs for SQL instances: MICROSOFT ## WID.Possible Reasons: lack of permissions, or transaction log corruption.”
I Contacted Veeam and they provided a Hotfix (info)
Basically it involved stopping the “Veeam Backup Service” and replacing 4 files in the following directory