Game installs fine, but when I go to update it to version 1.1.288 from 1.1.282 it starts, but immediately crashes with this error log.

"Game patch log
Update from version 1.1.282 to

Error modifying C:\GOG Games\MW5Mercs\MW5Mercs\Binaries\Win64\MechWarrior-Win64-Shipping.exe"

This is all using the offline installers. If anyone can verify for me I would most certainly appreciate it. Running in Windows 7 64. Cheers!

I managed to run the patch successfully on Linux though wine. All I can suggest is checking that file does exist and you have permission to modify it (although I expect the patch exe to ask for admin rights and be able to). Contact support or just bite the bullet and download the newer full installer. FYI 1.1.290 also exists now.

Yeah, I just downloaded the full updated version. I've had terrible issues with other game patches on GOG as well. Look at the 404 game patch mess with Adeptus Titanicus: Dominus. Those patch downloads have been 404 since the beginning and still haven't been fixed. So you have to download the full version every time it updates. Luckily I have a fairly fast connection.