it worked the first time i tried to play but now every time i go to play the game it gives me this error please help

Mmm, seems something went wrong with the configuration file fallout2.cfg.
Check it and see if there is a wrong path for the following files: critter.dat, master.dat and data.

Other suggestion are:
1) Try running the game as administrator.
2) Reinstall it outside the protected folder "Program Files".

I think dr.schliemann is right and I'd especially second suggestion #1: Try running the game as administrator. (Right-click it and select the option to run it as an Administrator) If it ran the first time, but never after, it's pretty likely admin rights.

Having this issue running on wine. Fallout 1 works great. Trying all the GameFAQ threads have been no help. Cfg, checking the paths, reinstall, etc. I cannot download any patches at the moment because I'm in the boonies and the downloads fail before I'm even at 10% I am running on Linux w/ Wine so the above is not applicable to my case. I only seem to get this error when running via the command line. Otherwise it's just a crash with no indication.

This error specifically means that Fallout can not find/access master.dat.
Just a guess, but it may be wrong letter case in some of the filename(s). GOG installer may have them mixed, while GNU/Linux environment is case-sensitive. Try to make all filenames in the Fallout installation directory either lower case or upper case and see if it helps.
And check what is configured in the fallout2.cfg. May be data file path is just wrong as well.

Ahhh, the case issue was the issue. Thank you! Once I made everything all caps like FO1 everything worked!

Sorry Im very new to this and facing the same issue, what do you mean exactly

I'm sorry for the late reply, however I will answer your question anyway.

I meant you should open the configuration file fallout2.cfg with a text editor, look for the paths of the files critter.dat, master.dat and data and check if they are correct, meaning that the files must exists in the same location of the hard drive.
Speaking of the other suggestions I gave, if you are using Windows 10 or 11, you could try to run the game as administrator and you should definitely not install games into the protected folder "Program Files".

Hey, sorry I’ m also very new to this but also trying to make it work on MacOs..
I downloaded a COG file but still has the message « Couldn't find/load text fonts » , I opened the file and everything seems fine.. do you have an answer for this problem?