Steam Forum

I've been trying to play all types of different Steam games, and they all install, but when I go to launch them, they don't open because I don't have the correct .NET Framework installed. I've tried installing .NET separately, but it doesn't seem to have done anything at all. Does anyone else have any problems like this or know of a solution?

Depends on what games you're trying to play. If you tell me I could have a look over at steamdb and tell you what needs to be installed.

As a rule of thumb, games that need .NET 3.5 and .NET 4.0 can't be in the same bottle.

Make sure that runtimes like .NET and VC++ stuff get all installed in the same bottles with the games.

When you say they won't launch you mean when you click on them in Steam nothing happens? How do you know it's .NET? A lot of my games have that pop up everytime you launch saying installing .NET for first time use, but the game still launches afterwards. I've always seen that pop-up on certain games, and I recall reading that's common/no problem.

Can you be specific what games you're having issues with, and how exactly they aren't "launching"?

An interesting issue developed for me about a month ago where most of my games won't play, on a bottle I had been using for a long time. For instance Portal 2, crashes right where it'd get to the main menu part, CS:S the same, Civ5 crashes when you try to play a game, etc. I'm fairly certain the issue is nvidia-drivers.. There's been numerous memory bugs with anything over 319.30 (i believe), and I know i tried 319.76, 325.15, and 331.20 and all versions would fail to launch/play many of my games. Downgraded to 304.117 and it works. May not be your problem, but figured I'd mention.