The error message “Object reference not set to any instance of an object” appears when clicking OK on the Scheduled Task Credentials screen.
This is a permissions issue.
The local administrators group must be granted Full Control for the Tasks folder.
To grant Full Control of the Tasks folder, perform the following steps:
- Navigate to C:WindowsTasks folder.
- Right-click the folder and select Properties.
- Select Security tab.
- Select the Administrators group and check Allow next to Full Control.
- Click Apply.