Note: This KB is applicable to only 5.x and 6.x, if this issue occurs in a newer version a new Active Full must be ran.
Job fails with error "There is no FIB [summary.xml] in the specified restore point."
This error is referring to an FIB ( File in Backup ) that is missing from that specific point. The file that is missing is the summary.xml file, which is xml data that holds data about that point and what the point contains.
There are two options. Either, apply patch 1 and higher for version 6.1 of Veeam Backup & Replication, or upgrade to version 6.5, to prevent this from happening.
Running a full backup should allow the job to run again.