I was playing Rocksmith perfectly fine this morning through Steam, just tried to start it up now but instead I get an error message saying "Unable to Initialize SteamAPI"m any solution?

Verify game integrity in steam, make sure steam overlay is there.

 

Run steam as admin once.

 

Google search turned up to reinstall steam.

 

https://www.google.com/search?site=&source=hp&ei=-QwAWNHNG8X5eLf5h9AC&q=unable+to+initialize+steam+api&oq=unab&gs_l=mobile-gws-hp.1.0.35i39k1j0i67k1j0l3.1744.2935.0.3737.6.5.1.2.2.0.221.672.0j3j1.4.0....0...1c.1j4.64.mobile-gws-hp..1.5.411.3..0i131k1j0i20k1.eG4hhf9n7CA

Just started getting this as well. After latest update I had to uninstall Rocksmith 2014 in order to get the Real Tone Cable to be recognized again. I tried it BEFORE patching it with the latest CLDC fix from back in October. It worked. But as soon as I applied the CLDC patch...I start getting this error. 

Unable to Initialize SteamAPI

I am starting to think this latest patch broke the CLDC fix. 

I finally got things working...8 hours later...MAN was that a pain in rear. 

No changes with the current install I had helped. I had to completely uninstall and reinstall Rocksmith 2014.

Which initially worked...then suddenly didn't.

So I did it again. Uninstalled and reinstalled. Then I ran the validate game cache check within Steam to see if it was corrupt as some suggested...but they did not tell me I need to do that twice in a row before it would fix the corrupt file for me. Nothing on the screen would have lead me to conclude that was how you did that. 

Then I did more research, because it was suddenly crashing in an even worse way now...and discovered it was setting the compatibility mode of the Rocksmith2014.exe file to Windows 8, and I needed to remove that setting for it to work in Windows 10.

Then after that it worked and stayed working after playing the game up patched a couple times in a row. Fingers crossed, I installed the CDLC patch...it worked. 

Only thing I am having trouble with now is loading my backed up game file that has all my progress saved. The latest patched version doesn't look to be saving it exactly the same way? Maybe? Don't know yet. Gonna have to research that more. 

Oh, and there were multiple restarts mixed in there as well. Not sure if they helped at all. 

I finally got things working...8 hours later...MAN was that a pain in rear. 

 

No changes with the current install I had helped. I had to completely uninstall and reinstall Rocksmith 2014.

 

Which initially worked...then suddenly didn't.

 

So I did it again. Uninstalled and reinstalled. Then I ran the validate game cache check within Steam to see if it was corrupt as some suggested...but they did not tell me I need to do that twice in a row before it would fix the corrupt file for me. Nothing on the screen would have lead me to conclude that was how you did that. 

 

Then I did more research, because it was suddenly crashing in an even worse way now...and discovered it was setting the compatibility mode of the Rocksmith2014.exe file to Windows 8, and I needed to remove that setting for it to work in Windows 10.

 

Then after that it worked and stayed working after playing the game up patched a couple times in a row. Fingers crossed, I installed the CDLC patch...it worked. 

 

Only thing I am having trouble with now is loading my backed up game file that has all my progress saved. The latest patched version doesn't look to be saving it exactly the same way? Maybe? Don't know yet. Gonna have to research that more. 

 

Oh, and there were multiple restarts mixed in there as well. Not sure if they helped at all. 

What setting do I need to remove to get it to work?