omg thx! I got a heartattack when I read this message xD

Not to be cruel to anyone, but you probably could solve most of your issues by exploring the client a little before wildly installing.

To the point of finding the cog, at the least.

This issue still exist and not fixed. What the **** are you doing man! It has been months god damn it!

goddamn is one word

When the solution of "RottynDawg" does not work... try this:

Change the following entry:
Install game to "C:\Program Files (x86)\Galaxy Games" (default setting)
to
Install game to "C:\Games Galaxy" (folder itself create)

Then GOG installed the game.

I'm trying to update Witcher 3 and none of the suggestions helped.

All paths are pointed to a drive with 35GB of space and the game is already installed. Seems it's checking C for available space even though it's not set to download or install there.

And I can't find a direct download for the patch either.

Tried that:

"1. Checked the box to "Manage all folders manually".
2. Manually created a folder for those locations. (This is where GOG Galaxy failed)
3. Pointed the two locations to that folder. "

did not help. After I uninstalled game to import it again from folder I kept, and now I cannot launch game from GOG galaxy. I yet have to try patch game by downloading patch manually.

edit: even "retry" button next to "Installation failed" do not work ...

edit2: finally! I had to run gog galaxy as administrator and it works now - only problem is you have to do it on .exe file, because it do not work on shortcut, also there is no point now to have gog galaxy on startup (unless there is a way so it always run as admin, even on startup).

edit3: ;( now I cannot change language -_- edit3b - apparently game have language I've chosen, but in gog galaxy it still display "English" - so better do not mess with DLC because it will rollback to english anyway ...

Awesome! This worked for me, but only after I "uninstalled" the previously failed installation.

After uninstall use the import folder under manage

I've got the same issue and tried every proposed solution until now (uninstall/reinstall game, uninstall/reinstall galaxy, delete data folders etc.). None worked!
I only solved it by fixing the security options on the partition using (right click)->Properties->Security->Edit and there remove any funky named users (created by installers) and change the permissions for Authenticated users and Users to everything except Full Control.

@Alexeht: Seems like you have the same problem I had.

Galaxy devs, you should change the error message to something more relevant!

I had to just download and install the game to my Downloads folder. Couldn't even get it to download to a folder on the Desktop... craziness.

No... I have the feeling there's a handful of directories that are hard coded into the kernel that require admin access to change. That's my impression of it anyways.

I suppose i could be wrong...

Solution -

Find a directory it WILL install to without the "out of disc space" error.
Chang the Gog.com Client downloads folder to that directory
Download/Install the game
Move the installed game folder to the directory you want (eg. where it should be)
GoG.com Client will say game is corrupt and after a few clicks will remove it from the installed games sidebar
GoG.com Client now gives you the option to install it again
Change the Gog.com Client downloads folder to the directory you wanted in the first place
Click the drop down "More" box and select "Import Folder"
Import the folder from the location you moved it to (eg. where it should be)
Take a short nap while the badly optimized verification process runs.
???
Profit

Could be bad sectors Check the Drive for bad sectors