403 ERROR WHEN TRYING TO DOWNLOAD
Please use GOG Galaxy to download your files. This application uses different means of authentication than browser links, and using it is practically guaranteed to fix this issue. You can find it here. Our browser download links are IP-based, to accommodate browser download resuming. This works under normal circumstances, but, unfortunately, we have learned that if a user's connection assigns a different IP when connecting to our site, and then a different IP when the actual download is initiated with our file hosting provider, an IP mismatch occurs, resulting in the 403 error. We are currently unable to resolve this issue, whilst preserving our users' ability to resume browser downloads. It may be possible for your network administrator to modify your network setup so that you are issued the same IPs for both GOG.com, and our file hosting provider's servers, which you eventually get redirected to. Unfortunately I cannot guarantee if this will work, nor if the network administrator would agree to making such a change.
I CANNOT SELECT A DIFFERENT INSTALLER LANGUAGE THAN "ENGLISH"
This is a known glitch and will be fixed as soon as possible. We apologize for any inconvenience this might have caused. If a game has only one installer (which contains all language versions), only the English language will be displayed. However, if you download and install the game, you should see that it contains all the language versions. Please download the "English" installer, and select the language in-game.
INSTALLATION FAILED WITH CODE: -3 CHECKSUM ERROR
Your files must have become damaged while downloading. We do not advise downloading manually through a browser, as this offers no error protection.Click here to find out how to fix this issue.
INSTALLER FILES MISSING
You must download all installer files, as per the error message. Without all these files in one folder, the installer will not work. Please go to your Library in order to download all the "parts".