Yes, no-one can play at the moment. There really is no point in people telling us they are having the same problem. Unfortunately, the only solution is to wait for Valve to release a fix.
This error happens with all mods, I tried to play grey, underhell and black mesa and get the same error. Just putting that out there.
Yes, it’s a problem with an update to the 2007 SDK as has been said.
Just another Guy who joins the “Me Too” Wagon, UNfortunate timing fo me tho… I installed the Mod with SDK 2 days ago, and was able to play without any trouble at all. I was on the Offices Part…
Yesterday’s weird update screwed up all. I hope VALVe takes a look on this Soon. As you guys already mentioned, it’s a Source SDK 2007 problem. (Because trying to open the SDK alone gives the same error) Yesterday, when i got this problem, there was no thread with this, so i thought it was on my end, today i redownloaded the SDK, with no success in the End, so everyone, Save yourselves time, and DON’T Download again the SDK. It won’t work. (Source SDK 2006 Does works though)
So I guess, this will just require Patience from us, as the Black Mesa Dev Team, can’t do much about it (As it’s NOT a Black Mesa Problem)
FInally, i wanna Congratulate you guys, This Game is Graphically Stunning! Can’t believe how much work you put in this, All the Voice work! The Soundtrack! Hats off to you Dev Team, Waiting Anxious for Xen Chapters! Take your time if this is how it’s going to look after all 
thanks guys now I will make sure to start Steam with the internet turned off 
Back in a minute
I know it’s just adding to the masses, but that’s what gets attention. Is there anyway I can find logs for this error, so maybe I could post them?
It made it to the steam forums. There are a ton of broken mods after the update, let’s wait if/when valve reacts.
https://forums.steampowered.com/forums/showthread.php?t=3189787
brb making a non-steam version of BM just in case
I read this thread and immediately backed up my Source SDK files prior to the upgrade.
After the upgrade was finished, I closed Steam and restarted.
Found out that it’s working because of the backup that I made and placed into a desktop folder. When I renamed the files and tried to run BM, got a message stating that Steam needed to download Source SDK Base 2007. So, BM was able to play because it’s accessing the backup files.
I just installed yesterday, didn’t even cause the resonance cascade yet.
Now this is just an idea, no one has to do it, but if someone could host a .zip or .rar of their working backup of Source SDK then we’d at least have a temp fix.
[COLOR=‘DarkOrange’]~Greetings[/SIZE]
[COLOR=‘Sienna’]As you guys know, the today’s Update for Source SDK Base 2007 came bugged. We got a coding branch on the SSDKB2007, something with the engine launching. All I know is nothing far than you guys know, but I noticed a issue in the graphics redering. That may explain the crash AFTER the load.
Let me explaing:[/SIZE]
[COLOR=‘Lime’]I have a real time thermometer on my CPU and my GPU. Also, I have a log with all my GPU activity. I watch closely ervery action of my CPU and GPU. Allways after the load of almost all Source Engine Games, my CPU and GPU get a low starting activity and a average activity when playing. When the game is loading, it gets no activity, so when it fininshes the load, it simply stops. That’s pretty normal for a crash, BUT, it gets NO ACTIVITY, so, there is no rendering coming from the engine. What explain that is: That the game is not even trying to launch.[/SIZE]
[COLOR=‘Sienna’]So, what I have to say is to erveryone waits paciently to Valve launches a Patch… I looking foward to it, because its not a hard thing to do, its just a code branch. But how could they do this in such opporturne time? Like… Half-Life 3 getting it’s name a patent … Half-Life 2 will be in offers very soon… Must be some Engine Study by the part of the developers or only a normal update that got wrong. Well guys, just wait :freeman:[/SIZE]
[COLOR=‘DarkOrange’]~ Best Regards =D[/SIZE]
Was the pimped text really necessary ?
Black Mesa is working fine for me. Was it just fixed or am I some special exception?
[COLOR=‘DarkOrange’]I think update is out! My Steam just asked for a update for the Source SDK Base 2007. Lets see if they fixed it =D [/SIZE]
my steam didnt ask for anything, I guess its gonna take time for some?
same here 
nope no fix yet
No updates on my steam client neither…
[COLOR=‘DarkOrange’]Greetings![/SIZE]
[COLOR=‘Red’]Guys, Steam did launched a Patch for Source SDK Base 2007. If Steam didn’t warn you about, try launching Source SDK Base 2007. If nothing shows, click with right button on it, then go in properties, then Updates and select “Always let this tool updated” (Or something like, my Steam is in portugish). Now try again launching it. [/SIZE]
[COLOR=‘Sienna’]Well guys, have a nice gaming. This mod is just AWESOME. If you need anything, send me a PM, I’ll try help you.[/SIZE]
[COLOR=‘Yellow’]~ Best Regards!![/SIZE]