ABR 11 - Centralized vault managed by storage node is no longer usable

I`m using Management Console to access the vault.
If i login to AMS , click Vaults -> Centralized -> "My Vault" i get the following failure:

Code: 9,371,651(0x8F0003)
LineInfo: 0x9A79F20828BCC7D;

Module: C:\Program Files\Acronis\AMS\ManagementServer.exe
Message: The running task has been canceled.

I tried using different credentials but it generated same failure.

Then I tried to use a Acronis Management Console on a client PC which is still version 10.
When I try t access the vault using this applition i do get a

"Error opening file" -> it's german so detailed message is "Fehler beim Öffnen der Datei".

Any ideas why this has happened and how to fix it?
I checked disc space on Storage Node Server and Vault location. Both OK.
I tried turning off and on the machine.

Thx for any help,
Matthias Sandmann