Unable to login to Plesk: Unable check file existence: Unable to logon user

Symptoms

• Unable to login to Plesk with the errors:

  PLESK_INFO: ERROR: Exception: Unable check file existence: Unable to logon user (IAWEB402Plesk Administrator): (1326) Logon failure: unknown user name or bad password.<br> at LogonUser(IAWEB402Plesk Administrator)(CClientProfile::logon line 146) at Plesk impersonation(PipeServer::ServerThread::impersonateWithoutProfile line 787). ERROR: Uncaught exception ‘Exception’ with message ‘Unable to execute proc_open: Unable to logon user

  ---

  PLESK_INFO: ERROR: Exception: The system cannot find the file specified. (Error code 2) at Unable to connect to pipe .pipeP_314e7936-44c1-4035-9726-2d19f0286ca0<br> at (Con::ClientOverlappedPipe::create line 503)<br> at get shared instance of PleskSrvClient(PleskSrvClient::getInstance line 337)<br> at Unable to get administrator password:(zif_get_admin_password line 249) (Helper.php:68)

• Restart of the Plesk Services Monitor > Plesk Management Service may fail with the following error:

  The service cannot accept control messages at this time. (Error code 1061) at ControlService 'PopPassD' with code 1

Cause

Processes PopPassD and plesksrv are stuck.

Resolution

1. Connect to the server via RDP
2. Kill PopPassD and plesksrv processes in Task Manager ( Ctrl + Shift + Esc ) > Processes tab.
3. Start Plesk Management Service in Plesk Services Monitor (available in the tray).