Blank pages after upgrading to v3.3.1

I’m seeing white pages since upgrading to v3.3.1 (though granted, it could also be down to something else).

This is my index.php:

include '../vendor/autoload.php';

$kirby = new Kirby([
    'roots' => [
        'index' => __DIR__,
        'cache' => __DIR__.'/cache',
        'sessions' => __DIR__.'/sessions',
        'root' => $root = dirname(__DIR__),
        'site' => $root.'/src',
        'content' => $root.'/src/content',
        'snippets' => $root.'/src/patterns/components'

echo $kirby->render();

The panel is still accessible, and my content appears there.

If I comment out the content root, I see the Whoops! debugger, which says: The home page does not exist.

What might have changed in recent versions for pages to stop appearing?

I’m using PHP 7.4

What happens, if you use PHP 7.2 or 7.3?

Ah! I synced my submodules, and this linked them to the master branches rather than the version-specific branches I’m currently using. Pointing my submodules to the right branches fixed this issue.

TL;DR: user error :face_with_hand_over_mouth: