Android dynamic feature module, resource not found

You can always access the resources from the main project inside the dynamic module, so you could just put your resources for the dynamic module in the main app, and then use the R.java from the main App.

However, the proper way to open these resources is to use SplitCompat.install(this) inside the dynamic delivered activity

I had an exactly same problem; fresh install crashes with Resources$NotFoundException, but subsequent upgrade works OK (the dynamic module is not downloaded again). But my case was slightly different, because instead of starting an Activity in the dynamic module, I wanted to load a Fragment through Navigation. In that case, I should have just navigated and let Navigation do its thing without manually checking the module was loaded or not (refer to https://developer.android.com/guide/navigation/navigation-dynamic for more info).

// Just navigate without calling splitInstallManager.installedModules.contains()
findNavController().navigate(DynamicDeliveryDirections.actionDynamicFragment())

If you want to start an Activity, you do need to check whether the module is loaded or not, as you are already doing. I suggest you take a look at Google's example, which does exactly what you are trying to do.

https://codelabs.developers.google.com/codelabs/on-demand-dynamic-delivery/index.html?index=..%2F..index#1

As for my case, I had to make sure the package names were correct. For example, if the main module's package name is com.example.foo and dynamic module is com.example.foo.dynamic_activity, then starting the Activity in the dynamic module would look like the following.

Intent().setClassName(
    "com.example.foo",
    "com.example.foo.dynamic_activity.DynamicActivity"
).also {
    startActivity(it)
}

This seems to have been a bug in com.android.tools.build:gradle:3.2.1 When I upgraded to 3.3.0 the problem resolved itself.

Hopefully it might help someone else who has this problem...