In the Windows 8 Task Scheduler, I have set up a scheduled nightly task to update Windows Defender.  I turn off auto updates.  Instead, I have Windows download the updates, but let me decide when to install them.

 

So after, making the scheduled task, I attempt to run it manually (just to test it).  Every time I do so, no updates occurs, and the task deletes itself.  I attempt to recreate it, but the same result repeats itself.  Any reason why it would delete itself? I've compared it to the "Scan" task, and all of the triggers and options are the same. The time to run, and the command parameters are the only things that are different.

I attempted exporting my scheduled scan task to XML, and then importing it as a new task.  Step by step, I make changes to several parts of the task (the time to run, the name and the description).  Each time I make a change, I save the task and run it (at this point, a full scan task).  Then I change the parameters to -SignatureUpdate, which runs a definitions update.  The task deletes when I run it.

Windows Defender is supposed to be updated by the Windows Update service, perhaps this is relevant. 

Correct, but you are able to schedule updates using the Task Scheduler if you prefer to manually update Windows.  It's no different than if I were to update Windows Defender using the Update tab. 

I still have a little script to update Windows Defender without show the consol window, you can create a scheduled task that run this script when you want

http://www.mt-megatechnique.com/out/WinDefUpdate.vbs

I still have a little script to update Windows Defender without show the consol window, you can create a scheduled task that run this script when you want

http://www.mt-megatechnique.com/out/WinDefUpdate.vbs

I think we're in business - you are the man!

Hmmm I run the script at a command prompt.  It works.  I load it into a task.  I run the task and it takes forever.  Windows Defender does not update and the task is deleted.  Go figure.

OK this is strange.

 

I got my own task working (without the script).  What changed it?  I called my original task "Windows Defender Update".  I changed the name to "Windows Defender Update Task".  Now it works.

 

Huh???

Edited December 31, 201510 yr by JodyT

Glad you have it working

This probelm with the name is a bit strange, may be an old task with the same name were corrupted and may cause this problem but I don't realy know why

Thanks for all of your help on this.  And now with Windows 8 being EOL, I've completely turned off and disabled the Windows Update Service, cleared out the Software Distribution folder, and Windows Defender still updates on schedule.