I'm having some issues with w19tax.exe access violations and found your post.

Your setup is not clear though I assume you have a Server setup.  Hopefully by now you have this sorted.  If so a summary would be helpful.

My problems also seem to be more centered on PCs that were upgraded from win 7 to Win 10.

See my post here with all the solutions I am trying.

https://proconnect.intuit.com/community/lacerte-discussions/discussion/w19tax-exe-fatal-application-...

Probably the first thing I would do is a FORCE Websetup (Step 2) from your IT workstation, if you have one, and then do the FORCE setup for each of the clients from the Server (Step 1) to get then all in alignment.

https://proconnect.intuit.com/community/help-articles/help/how-to-perform-a-force-install-of-lacerte...

If you have AV (we have ESET) I have found that it's locking Lacerte files and adding the AV exceptions is very important.