SymptomsWhen trying to add or remove scheduled tasks in the Plesk scheduler, The following error message is displayed:
SchedulerManager::set() failed: listmng failed: Unable to restore user scheduler:
System.ArgumentException: The parameter is incorrect
CauseWindows task scheduler is not functioning properly. It cannot create/delete tasks. Most probably, the reason of this issue are corrupted RSA keys in system. RSA keys are stored in the %ALLUSERSPROFILE%\Application Data\Microsoft\Crypto\RSA folder.
ResolutionCorrupted RSA keys need to be removed using the following steps:
1. Stop the Windows Task Scheduler:
Start, Run, type sc stop Schedule
2. Rename the S-1-5-18 and MachineKeys folders in
3. Restart the Windows Task Scheduler
Start, Run, type sc start Schedule
4. Reboot the server.