Hi Khaled1989, this is a typical iOS issue, which is discussed here for instance (there exist other threads too):

http://stackoverflow.com/questions/7853136/couldnt-register-with-the-bootstrap-server

Dear all,

It is the vuforia sample application, i changed it's name to "Epic MAR Cloud" and it worked for me very well

but suddenly it stopped and doesn't run and printed this message:

Couldn't register com.qualcomm.qcar.testapps.Epic-MAR-Cloud 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.

so i changed the application name to "Epic MAR C" and it worked!!!!!

what's the meaning of this Message????!!!!!!!

Firstly: it is good to run problems via sites like StackOverflow, especially that answer to your question will be for sure there (I had myself similar problem). Kill app, restart phone, restart Xcode - should work else Stack ;)

Secondly: what do you mean that Xcode dosn't support Vuforia ?? you can run and develop apps from Vuforia... Oo

Vuforia isn't supported by the XCode simulator. Are you having any issues when running your app on a device?

Hi Khaled1989,

could you specify a bit more details here; 

were you running the CloudRecognition sample app from the Vuforia samples ? (Android, Unity, iOS ?)

or is it your own App ?