Upgraded from 5.4 to 5.5 getting 1100 errors in Mono

Hi,
I just upgraded from 5.4 to 5.5 getting 1100 errors in Mono when I compile. - Any Ideas?
I installed 5.5 on drive C: to be sure to be able to switch back to my 5.4 on drive d:. - maybe this is a problem.
.. must be a kind of Setting, maybe. I was using Mono /.NET 4.0 Target framework normally. - I tried all other settings with 5.5.
My PlayerSettings worked all the time with .NET 2.0 Subset. - Active Runtime in Mono is Microsoft.NET and worked all the time with 5.4.

Thanks in Advance,
wohl
Here is the first Warning:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(5,5): Warning MSB3245: Could not resolve this reference. Could not locate the assembly "Assembly-UnityScript-firstpass". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors. (MSB3245) (Assembly-UnityScript-firstpass)

 

That's usually more like the last error. The assembly didn't compile due to other errors, which eventually results in this error when it's looking for the compiled assembly. New versions of Unity often have breaking syntax changes. You just need to find the compile errors and fix them. If you're using assets from the Store you may need to upgrade the asset to a version that supports the Unity version you're using.

 

I had this issue upgrading to 5.5 too - I closed down Unity, deleted the Library folder within my project, and restarted Unity again. After it reimports everything it should work ok.

 

Thanks you both for the feedback. - I deleted the library folder and restarted. - The game runs in editor like before. But Mono is the problem. I get the 1100 errors again and here are simple example why I think the scriptversion must be a problem:

Mono never said this synthax is wrong on this. - Do you have any ideas?

 

I found one of the problems. - Mono tried to compile the .js files. - 2 of them from the StandardAssets CharacterMotor.js and FPSInputController.js. - Thats why the syntax produced so many errors. - But I deleted them, now I can not compile because Mono misses the files and gives 2 errors that each of the files could not be found. - What can I do?

 

I found a major problem. - Mono tried to compile 2 .js files from the standard assets: FPSInputController.js and CharacterMotor.js - thats why the synthax was wrong. - I deleted the files. And now Mono complaines that the files are missing. - What can I do?