Hammer doesn't start: MountFilesystem( 241 ) failed

Since today, starting up Hammer 4.0 gives me the following error:

MountFilesystem( 241 ) failed:
SteamMountFilesystem(3912,242,0x339fbfc=,0x339fd0c) failed with error
116: Cache needs repair

Any suggestions or idea's on what this would mean, or maybe someone
else has encountered this before? It's obvious the caches need repair,
but how would that be done? Perhaps removing and reinstalling the SDK?

I'm not sure - but it sounds like you have to do one of the following or perhaps all:

1 - Delete the sourcesdk.gcf in the "SteamApps" folder

2 - Delete the "bin" folder in the "sourcesdk" folder

3 - Delete the entire "sourcesdk" folder

I'd try 1 first, then 2 and finally 3 ...

Make sure to back up any stuff you have in there that don't come with the SDK first ...

Nevermind, solved it by running the SDK from the Steam Games menu. It
then validated my files and after that I was able to start Hammer as
usual.

This error occurred after I had extracted some materials from the
source materials.gcf to my hl2materials folder. Shouldn't give any
trouble as far as I can see, but seemingly something did go wrong.

I'm gonna mark this topic as answered and leave it here, just in
case someone else gets the same problem. Thanks for the reply anyway. :smile:

Ah - I'm guessing you had a gfc opened in GFCScape when you got the
error? That will cause problems - while the file is open in another
prog steam can't write to it and sees it as the file being corrupt ...

No, I had no .gcf files open at the moment I tried to start Hammer.

I had the same problem lasr week, actually. Bit weird but oh well :smile: You can use Hammer as normal from a normal desktop shortcut after doing this.

And now I'm having the same problem again, after messing about the filesystem_steam.dll and trying to get VRAD to work, but re-installing the SDK doesn't work (even if I delete the whole sourcesdk directory). Running HL2 or another program to verify files seems to do the trick, while visiting steam://validate/211 doesn't...