“Default Activity Not Found” on Android Studio upgrade

Question

I upgraded IntelliJ Idea from 12.0.4 to 12.10.

Now all the modules in my Android project give the error:

Error: Default Activity Not Found

Answer 1

This occurred to me after my PC restarted unexpectedly.
Strangely, I had made no changes and still got this error.
None of the above helped me. What solved my problem, is this.
Step 1:


Step 2:


Step 3:

If this doesn't solve the problem give other tries.

Try 1:

File -> Invalidate Caches / Restart...

Try 2:
check whether these following two lines

are in your launcher activity declaration in manifest.xml

Try 3:

1. Click as shown:
   
   
2. Run / Debug Configurations opens.

if this also doesn't help.
Try 4:

1. File->Export to ZIP.
   and
   
2. Import it as new project.

Best luck.