Unable to access Acronis Backup extension in Plesk: An error has occurred. Please try again later or contact support

Symptoms

• Unable to access Acronis Backup extension in Extension > Acronis Backup. The following error is shown in Plesk UI:

  PLESK_ERROR: Error: An error has occurred. Please try again later or contact support.

  OR:

  Access to the extension is possible, but no data is shown and the same error appears when trying to access the backup console from extension interface.

• Acronis backup log file /usr/local/psa/var/modules/acronis-backup/srv/log/main.log contains following records:

  CONFIG_TEXT: [INFO] MmsResponse: {"error":{"code":-32000,"message":"Can not found backup plan: "},"id":3969,"jsonrpc":"2.0"} /var/lib/Acronis/AgentCommData/mms-comm/out/a34cb12e-2f3a-4f23-b21f-c0bd08e000ec
  [INFO] SrvResponse: {"error": {"code": -32059, "message": "Backup plan is not found."}, "id": "5a5ce6644adc1", "jsonrpc": "2.0"}
  [INFO] MmsResponse: {"error":{"code":-32603,"message":"Error code 401 and raw message

• The following error occurs on attempt to start a backup from the Backup Console directly:

  CONFIG_TEXT: Backup doesn't start:
  Backup failed
  None of the items selected for backup were found.
  Device example.com
  Plan name webcp
  What to back up Entire machine
  Where to back up

• Login to cloud.acronis.com works fine.

Cause

The issue happens because of a token used for communication with Acronis cloud was marked as 'expired' and then revoked on the cloud side.
This happened because of there were no calls from the extension UI to the cloud for a week.

Resolution

Register the server once again with the following steps:

1. Login to Backup Console directly via cloud.acronis.com.

2. Delete a Plesk Server from the console (backup will not be deleted):
   

3. Login to the Plesk server via SSH and execute the following command replacing username and password with the correct ones:

   # /usr/lib/Acronis/BackupAndRecovery/AmsRegisterHelper register 'https://cloud.acronis.com' username password