Windows 7 to 10 Upgrade stopped working after over 600 succesfull deployments

[vidsid]

I've been pushing the upgrade from Windows 7 to Windows 10 1607 for a couple of months.  Have done 600+ machines succesfully.
All of a sudden, starting a few weeks ago ALL upgrades are failing and rolling back to Windows 7 with one of the following errors:

The task sequence execution engine failed execution of the task sequence.
The task sequence manager could not successfully complete the execution of the task sequence.

I suspect it's failing at the Intel HD video driver that's incompatible because I have to accept the removal when manually updating.  Before, it would just delete and add the Microsoft generic, and I'd have to load the Win10 Intel Driver later in the task sequence. ...but that's just a guess.

Where should I look and what do I look for?  Why all of a sudden would this stop working?

 

[vidsid]

It was a combination of 1607 being out of date and forgetting to check 'ignore dismissible compatibility messages'