If you have World Engine 3.0, 3.5, or any other fan fork installed, do not install over it. You must uninstall first:
Why this fixes crashes: Android prevents installation of an APK with a different cryptographic signature. A clean uninstall removes the old signature conflict.
Even after the Super Mario Maker World Engine 4.0.0 download Android fix installation, you might experience lag or stuttering. Here is how to tune it:
Fix for crashes when saving levels: Grant the app storage permissions manually. Go to Android Settings → Apps → Super Mario Maker World Engine → Permissions → Enable "Files and Media."
Follow these exact steps to avoid the most common failures:
Fix for "Black Screen": If you see a black screen, you missed step 5. The engine is looking for sprite sheets and cannot find them. Alternatively, delete the folder and repeat the copy process.