As per Pegasus:

The taskresults ini should exist in the following location by default:

C:\ProgramData\Pegasus\Scheduler Server

To resolve this give full permission to the user account running the tasks on top level at c:\program files x86\pegasus and c:\programdata\pegasus 

Also ensure that the scheduler dynamic share is present and shared correctly. If the above does not resolve the issue (but should do) then also try the following; Stop the Scheduler service, Change the logon from local system account to a network admin account

Restart the scheduler service.