Article ID: 1848, created on May 15, 2007, last review on May 11, 2014

  • Applies to:
  • Plesk for Windows


When 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


Windows 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.


Corrupted 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

%ALLUSERSPROFILE%\Application Data\Microsoft\Crypto\RSA

3. Restart the Windows Task Scheduler

Start, Run,
type sc start Schedule

4. Reboot the server.

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