What gives? The DLC is miniscule and there's plenty of space on all my disks.

[url=]https://i.imgur.com/rY7y44M.png[/url]

Maybe you had this idea, but did you check the support page of the game, maybe it is a known problem which has a solution?

Try re-downloading the base game, and then the dlc.

Couldn't find anything on it anywhere. It's exactly what I was trying to avoid, since I've got some mods in the game and the download is fairly huge, and space on my drives are pretty limited. I've started downloading, though, but I have no idea why it'd help. Having to reinstall everything with such a low chance of success is annoying, to say the least.

It's frustrating that the installation files even have these checks - it should just ask me where I want to install, and judge available space based on that.

If you don't mind losing your mods, Galaxy should be able to check if the installation needs repairing. You could just import the game there, repair if necessary, and then install the dlc. This will get rid of your mods, but at least you won't have to redownload the whole thing.

Have you tried running the installer explicitly as Admin (right-click => Run as administrator). Maybe an access rights issue prevents the installer from determining the free space correctly.

Maybe it won't let you install on D drive, which would be strange.

Always try to install game and dlc before the mods.

Try defrag the disk.

probably mods corrupted the checks gog installer does before installing dlc and hence the errors, its probably checking some unknown drive for the game