By skyforbes 
An error has occurred for task. Error message: The following error was reported: A Specified logon session does not exist. It may already have been terminated.
Simple steps to fix the above error.
- Login as Administrator
2. Go To Local Security Policy
3. Expand Local Policies > Security Options
Under right hand side panel (Policy), look for
Network Access: Do not allow storage of passwords and credentials for network authentication
4. Double click on that.
5. Change Enabled property to Disabled
Happy Scheduling !