App installation failed due to application-identifier entitlement

I had this problem with an iPhone app, and fixed it using the following steps.

• With your device connected, and Xcode open, select Window->Devices
• In the left tab of the window that pops up, select your problem device
• In the detail panel on the right, remove the offending app from the "Installed Apps" list.

After I did that, my app rebuilt and launched just fine. Since your app is a watchOS app, I'm not sure that you'll have the same result, but it's worth a try.

I had this problem and was not able to resolve it without deleting and reinstalling the app (messing with provisioning profiles, as some here suggested, did not help).

However, I did not lose my existing test data. Here's how to do that, for anyone having this problem in the future:

1. Before removing the app, open the Xcode "Devices" window (that's cmd-shift-2).
2. Select your device and find your app in the "Installed Apps" list.
3. Click on the gear icon and select "Download Container...". This will copy all of the app's data to your Mac. Save that somewhere for now.
4. Delete the app and reinstall it from Xcode. Kill the app from Xcode (click the stop button), so it's not running.
5. Back in the "Devices" window, click the gear icon and select "Replace Container...". Select the data that you downloaded to your Mac in step 3.

Xcode will then restore your previously saved app data. You now have your old test data back, and the app should run.

Delete any previous versions of App from your iPhone and then Clean->Build and Run again. Your app should run smoothly on your Device.

Also, please make sure you have not selected Distribution Certificate in your Project Settings while trying to run your project directly on your device.