Challenge
During a tape related process in Veeam Backup & Replication the error “Tape positioning error: An attempt to access data before the beginning-of-medium marker failed” is thrown.
Cause
The most common cause of this is faulty tape.
Solution
If there is no content on the tape try erasing it, if the issue persists try a different tape. If the task is successful with a different tape, the tape that caused this error is most likely faulty.