Hi Justin. Thanks for your input. I ended up uninstalling LF manually (deleting application files, Common Files, AppData files, etc and removing all related registry keys). I then rebooted the machine and tried the LF 9.2 install routine again. That took care of the issue. LF 9.2 is now up and running with all of the components (scanning, Admin Console, Snapshot, PhotoDocs, etc.). We're good to go. Thanks again for the response.

I had a few steps for my customer too. Hope this helps someone out there.

They were running LF Client 9.1 but the environment was recently upgraded to 10.4.1. They had some mixed installations (OCR 10.4.1 and LF Client 9.1), I'm not sure how that even happened.

After trying to upgrade to 10.4.1 and getting met with the "Installation failed. The installation will be rolled back in the background" message repeatedly, I did a couple of other things first.

Notes are below, with actual steps to fix the problem just in bold.

1. Went to Start>typed in "Appwiz.cpl" and right-clicked to open as administrator.
2. Went to Start>typed in "cmd" and right-clicked to open as administrator.
3. In cmd prompt, typed "Tasklist" and noted any line items for "MSiExec".
4. Typed "taskkill /pid (entered the pid number for MSiExec) /f" and hit enter. That killed any install processes that were stuck.
5. Went back to the appwiz.cpl window and right-clicked on any Laserfiche 10.4.1 components and uninstalled each one. Strangely enough, LF Client 9.1 was still present, though not showing on the Appwiz.cpl list even after refreshing.
6. Attempting to re-install LF Client 10.4.1 failed, but interestingly, it noted that LF Client 9.1 was still there.
7. Located the old LF Client 9.1 on the servers' installations folder and ran a repair install. After that, we could get further on Upgrading to LF Client 10.4.1, but it still wouldn't go all the way.
8. Using that same LF Client 9.1 MSi (Installer file), removed LF Client 9.1, then re-installed it, then removed it again (I'll explain).
8.1 There was a fragment of the LF 9.1 installation remaining even after uninstalling from Programs and Features that was preventing the 10.4.1 upgrade, so first we uninstalled (which still left the fragment, but created a state in which we could run an install, not just a repair install), then we ran a fresh install of 9.1, now with a full install, we were able to successfully uninstall and get it to fully remove.
8.2 The next step was to get 10.4.1 deployed, and now that no other LF Client installs were showing, it could do so.

9. Because LF Client 10.4.1 was able to have the install (green) progress bar make it all the way to the end before getting his with the same error message again (...unable to roll back, etc.), we tried a new approach (see below):

10. Copy/pasted the LF folder (yes, it's big, but this fixed it) onto the desktop and deployed the install locally instead of by navigating to a folder on the server - it finally installed correctly and tested just fine.