Android studio design editor is unavailable until after a successful project sync

Question

what is the actual root cause of this issue? I already sync with gradle files but eventually failed.

Answer 1

That could be fixed in one or two steps, depending on how nice is Android Studio today:

1. Try to sync your project with gradle files:

2. If that doesn't work, invalidate Android Studio caches and restart. That should fix the problem:

The reason behind the first solution not working could be related on gradle cached dependencies problems, but who knows