"Fatal Error" closes game immediately

[Vrekasht]

This seems to be a common one but, frankly I don’t really understand…anything…up to and including whether there was ever a fix found for it

Essentially, I just had my extremely full 1TB hard drive replaced with a 4TB hard drive; I don’t know if this matters but the new drive is D: instead of C:
Never had a problem when I used to play (solo, I never joined a multi server or anything like that). I had to stop because the update it wanted to do at the time was so large I literally had no more room for it on the old drive. Transferred the files to the new drive yesterday, updated, everything seemed to be fine. But, every time I try to play the game I end up with this message while the opening video is playing:

Fatal error:
[File:C:\B\tech_exiles\code\UE4\Source\conansandbox\conansandbox.cpp] [line: 417]
mounted paks num(203) not equal to expected paks num(201) and (0) optional packs not available. please verify your installation

…and I can’t get any further. Verifying the installation did absolutely nothing, I’m still getting the same message and the same result. I’ve never used any mods or been on a PVP server.
I’d really rather not uninstall and delete everything when I’m not certain spending probably seven hours re-downloading the game is actually going to fix the problem, has anyone ever come up with a surefire solution to this?

Sorry if this is a redundant thread but there doesn’t seem to be any actual official support for this game? And I’m at a loss as to what to do about it…

[DeaconElie]

Been fighting with this same{?} issue since I had to do a windows reinstall Thursday. Games are on a separate drive. I get as far as choosing to load or continue, doesn’t matter what I select I get an almost instant fatal error.
I’ve verified files, uninstalled, and reinstalled Conan and steam. With and with out mods. Cleaned scrubbed, reinstalled, reinstalled battleye, and I give up. I can play for 10-15 minutes as long as I don’t click “ok” on the fatal error warning. But it eventually shuts down.

[Narelle]

Go in the pak folder, sort by date, most files should have the date of your fresh install. Delete the rest of the files (you can try first with the paks with an older date than the install one if there are any). After deleting them, verify to redownload whatever is needed but missing and try to log.