Converting from much older versions (say C5 to C11) often the templates are not all in C11 so the “Templates missing” error will occur. Sometimes there are more missing than fit in the errors panel.
After this the App has the missing templates removed so is damaged. After clicking Yes the load continues. Clicking No seems to get stuck in a loop, so you have to click YES and recover the APP from backup.
The problem is after it finishes loading the App the Errors List is empty 
. I know this now, so I get a screen capture before I close the error message to have the list of problems. I’ve seen this in 9, 10, 11 and 11.1.
What I noticed today was the button still says “1 Error” … The errors list might still be there?
My Tip is to click the Errors button, which hides the errors. Then click the Errors button again and the missing errors appear!
Where this really is needed is when there are more errors than will fit like this one with 84.
Text of the error message for search:
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Generator
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Errors were found on merging template changes to the Application.
Templates missing from the Registry will be removed from the APP.
Do you want to save the changes to the APP?
File: C:\code\project\p.app
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Yes No
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