title: DTAssetProviderService could not start DTXConnection with Simulator
body: <p>After updating to Xcode 7.3 I am not able to run my app in the iOS Simulator.</p>
  
  <p>On every attempt I am getting the following error message:</p>
  
  <blockquote>
    <p>DTAssetProviderService could not start DTXConnection with Simulator 'iPhone …'. Check the system log for errors.</p>
  </blockquote>
  
  <p>I have checked the following <a href="https://forums.developer.apple.com/thread/43340" rel="noreferrer">Apple developer forums thread</a> but didn't any provide any solution. Suddenly when I have cleaned &amp; deleted the old app from the simulator and rebuilt, it works fine. This issue was not only for the first time. </p>
  
  <p><a href="https://i.stack.imgur.com/o66sL.png" rel="noreferrer"><img src="https://i.stack.imgur.com/o66sL.png" alt="Screenshot of quoted error message above."></a></p>
  
  <p>Can anybody explain this issue in detail?</p>
  
  <blockquote>
    <p>Mar 24 10:18:38  CoreSimulatorService[521] : com.apple.CoreSimulator.CoreSimulatorService 209.19 starting.<br>
    Mar 24 10:18:44  CoreSimulatorService[521] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:44  CoreSimulatorService[521] : Requested phone is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:44  CoreSimulatorService[521] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:44  CoreSimulatorService[521] : Requested phone is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:45  com.apple.dt.Xcode[455] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:45  com.apple.dt.Xcode[455] : Requested phone is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:45  com.apple.dt.Xcode[455] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 10:18:45  com.apple.dt.Xcode[455] : Requested phone is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 11:02:29  com.apple.iphonesimulator[712] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 11:02:29  com.apple.iphonesimulator[712] : Requested phone is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 11:02:29  com.apple.iphonesimulator[712] : Requested watch is is not available for pairing.  Assuming it has the capability.<br>
    Mar 24 11:02:29  com.apple.iphonesimulator[712] : Requested phone is is not available for pairing.  Assuming it has the capability. 
    Mar 24 11:02:31  CoreSimulatorService[521] : Could not register service com.apple.coreservices.lsuseractivity.simulatorsupport: Failed to lookup com.apple.coreservices.lsuseractivity.simulatorsupport: 0x44e</p>
  </blockquote>
  
  <p>My guess for this issue: I am not sure but my guess is when I updated Xcode, the iOS version updated to 9.3 but the app was already installed in the iPhone 6 Plus simulator when the old version (9.2) was installed. Therefore when I tried to run the app with iOS 9.3 I was configured for iOS 9.2 only, and due to incompatibility it crashed.</p>