Backups to Tape fail with an error "0xe00084f4 - An unknown error has occurred" and Tape drive is marked offline.

Problem

Backups to Tape fail with an error "0xe00084f4 - An unknown error has occurred" and Tape drive is marked offline.

Error Message

0xe00084f4 - An unknown error has occurred.

Error seen in event log around the time of the backup job failure

Log Name:      Application
Source:        Backup Exec
Event ID:      33152
Description:
"[10628]  Adamm Mover Error: DeviceIo: 06:00:07:00 - Device error 3 on ""\\.\Tape0"", SCSI cmd 0a, 1 total errors"

Cause

This issue is caused due to tape device being reinitialized when the backup job is active. Just before and after the above-mentioned event id 33152 the following events are also be logged.

Log Name:      System    
Source:        Service Control Manger
Event ID:      7036
Level:         Information
Description:
The Portable Device Enumerator Service service entered the running state.

Log Name:      Application
Source:        Backup Exec
Event ID:      58053
Level:         Error
Description:
The device state has been set to offline because the device attached to the computer is not responding.
Ensure that the drive hardware is turned on and is properly cabled. After you correct the problem, right-click the device, and then click Offline to clear the check mark and bring the device online.

Log Name:      System    
Source:        Serivce Control Manger
Event ID:      7036
Level:         Information
Description:
The Portable Device Enumerator Service service entered the stopped state.

Solution

Open Windows Services console and stop the "Portable Device Enumerator Service". Change the startup type to disabled.