Strange error by iOS Simulator – bootStrap server – couldn’t register …

Sometimes, when you try to run your project in iOS Simulator, you might get following strange error.

iOS iPhone iPad Simulator Hang Another instance error

iOS iPhone iPad Simulator Hang Another instance error


Couldn’t register with the bootstrap server. Error: unknown error code.

This generally means that another instance of this process was already running or is hung in the debugger.

Or you might receive an error as follows

Cannot launch in simulator while it is already in use.

Well, the reason behind prompting you such error is – “Same instance is already being processed by iOS simulator”. It means that iOS simulator is already running that project.

But, By using thing point, I will describe “How to avoid such errors?” & “How to eliminate/resolve such errors?”

1) How to avoid such errors ?

  • First of all, Go to Product menu, click on clean option.
  • Now, Do build before running your project. In most of the cases, developer directly clicks on RUN button. If we press build first, we can came to know about compilation warnings & errors. Executing RUN commands means avoiding necessary warning prompts from XCode & which is strongly not recommended.
  • Once you done building your project, check for all errors & warnings.
  • Once all errors & warnings are solved, check your iOS simulator. Is it already being used by any other project or is it being used by same project?
  • In short, just stop all the running projects which will ultimately stop the iOS simulator access by XCode.
  • Once you have ensured that no project is using iOS simulator & iOS simulator is no longer associated with any project, then click on RUN of your project to start testing using iOS simulator.

Yes, I know your pain to read & follow the things listed above. I am also a developer & I can understand that no-one want to do follow such formalities. But Prevention is better than cure. It is preferable not recommended.

If you follow above steps, you will not receive such errors as described in the top of the post.

2) How to eliminate/resolve such errors ?

When you face such errors,

  • Check for all of your projects being opened by XCode, go to each project window & ensure that non of the project is running/using iOS Simulator.
  • Stop the access to iOS simulator by any of the project of XCode.
  • Now, close unnecessary project windows, which can eliminate your confusion – on what project you are working :P :) ( Yes, I know, Most of use are used to work on multiple projects simultaneously :) )
  • If required, do reset the iOS Simulator.
  • If required, do quit iOS Simulator.
  • If required, do quit XCode also.
  • If non of them working at all even yet. I think you required to log out & log in again. Or System restart would do the best among all but highly not preferable :)
  • Also check with installed XCode versions. e.g. I have installed XCode3 & XCode4 both. So, XCode3 might be using simulator & you may be trying to run your project from xcode4 & that won’t work

Leave a Reply

Your email address will not be published. Required fields are marked *