Task Sequence has failed with error code 0x80070661

The other day I came across the below error message during OSD deployment in my lab, this threw me for a minute mostly because I’ve used the TS many times in the past without any issue.

I examined the SMSTS.log file and as soon as I saw the error I knew what the problem was, basically in my rush to get a system created to work on, I assigned an x64 application Software install into the TS (App-V client) to an x86 image!! Whoops!!

I ran through the deployment again with the correct version of the App-V client and as expected all was ok.