1. Backup to tape fails with an error:
The storage media is write protected
2. The tape media is LTFS- formatted
3. When you check Windows Event log, a critical error is shown: "The LTFS file system encountered an error"
LTFS (Linear Tape File System) is not supported by Acronis Cyber Backup 12.5: see p.14 in Limitations of tape device usage
Unmap or reformat LTFS media to generic data media.