FBSOpenApplicationErrorDomain code =4 error

Question

When I\'m trying to run iOS application in Xcode 6 in iPhone 6 simulator, I\'m getting error Unable to run app in Simulator.

And error code is:

Answer 1

This worked for me:

iOS Simulator -> Reset Contents and Settings... -> Reset

referenced from Qiita: Unable to run app in Simulator エラーの対応方法.

Answer 2

Just closing the iOS Simulator worked for me.

There is not always the need to reset the iOS Simulator. I did not even had to close Xcode.

Answer 3

This happened to me once when I added some assets as symbolic links (through ln -sf). Even installing to devices was failing.

After I removed the links and made a hard copy, it worked and error was gone.

Answer 4

As mentioned in the Xcode release notes, this error (along with a couple others) results from a timing bug. The workaround is to just retry.

See https://developer.apple.com/library/prerelease/mac/releasenotes/DeveloperTools/RN-Xcode/Chapters/xc6_release_notes.html#//apple_ref/doc/uid/TP40001051-CH4-SW1

Testing on iOS simulator may produce an error indicating that the application could not be installed or launched. Re-run testing or start another integration.

Also see:

https://devforums.apple.com/thread/248879?tstart=0

Answer 5

Reseting the Xcode will delete some bad junk which simulator has cached, so reseting is good option to resolve this issue.

iOS Simulator -> Reset Contents and Settings.

Answer 6

This problem probably started after we enabled background mode in our app.My solution :

1) Go to simulator
2) Hold cmd + shift
3) Tap 'H' key two times
4) Slide the application off to stop it running in the background.
5) Run again.

(Very tiring to have to repeat the above step each time I build and run)