There are few steps you could try to get away from this error.
Hope this helps!
thanks for your reply.
I have this problem with a newly created app and an newly deployment directory.
There is no other process who can access this file during running the Build process.
I’ve tried it several time – always same result
I can build an Android app when deleting the content of directory “Appicon.appiconset”.
But I can’t test whether an IOS app can be build without these files.
It seems just to be a workaround for building Android apps.
In Runtime URL textbox need to add sandbox URL instead of localhost
Problem has been solved by Mendix in “Build Native App v.1.0.90”