Backup Failure - Error code : 41, 3, 1060, 26

Hi, our company is using Acronis.11

When progress reached as 20% during backup,  this error appeared and stopped.

Could you let us know what can be root cause of this failure?

Especially, Error code : 26 "Invalid file reference"

Error Code: 41
Module: 307
LineInfo: e6792a5ee190dd9e
Fields: $module : agent_protection_addon_vs
Message: ProtectCommand: Failed to execute the command.
--------------------

Error code: 3
Module: 329
LineInfo: 1cd98aae889424f9
Fields: $module : disk_bundle_vs

Message: Backup has failed.
--------------------
Error code: 1060
Module: 1
LineInfo: b43e776571144dee
Fields: $module : disk_bundle_vs
Message: Failed to commit operations.

Errorcode: 26

Module:7

line Info: 89d94b01b483e29e

Fields: $module : disk_bundle_vs

Message: Invalid file reference.

--------------------