Backup fail because of "unknown user name or bad password" (Error code: 65520)

Hi everyone,

Our company use Acronic Backup & Recovery 11.5 build 11.5.38350 to backup our data. But recently, it's usually fail because of error code 65520. It's about once a week. Detail is below:

--------------------
Error code: 20
Module: 4
LineInfo: f35f747b3b21fb39
Fields: function : FindFirstFileW, filename : \\?\UNC\x.x.x.x\****\*****, $module : disk_bundle_vs_38350
Message: Access to the file is denied.
--------------------
Error code: 65520
Module: 0
LineInfo: bd28fdbd64edb8e0
Fields: code : 2147943726, $module : disk_bundle_vs_38350
Message: Logon failure: unknown user name or bad password
--------------------

Anyone used to have issue like this?
Thanks for any solution,
Tin.