Multisite setup (subdomain): Theme 'ceevee' does not exist, unable to display page

I use the ceevee skeleton and created a simple multisite by duplicating its user folder into /user/sites/foo.mydomain and /user/sites/bar.mydomain.
Both subdomain are configured to point to the same grav-multisite

However, instead of a running installation, I get:

Theme 'ceevee' does not exist, unable to display page.

my setup.php was copied from the docs and looks like this:

 * Multisite setup for subsites accessible via sub-domains.
use Grav\Common\Utils;

// Get subsite name from sub-domain
$environment = isset($_SERVER['HTTP_HOST'])
  : (isset($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : 'localhost');
// Remove port from HTTP_HOST generated $environment
$environment = strtolower(Utils::substrToString($environment, ':'));
$folder = "sites/{$environment}";

if ($environment === 'localhost' || !is_dir(ROOT_DIR . "user/{$folder}")) {
  return [];

return [
  'environment' => $environment,
  'streams' => [
    'schemes' => [
      'user' => [
        'type' => 'ReadOnlyStream',
        'prefixes' => [
          '' => ["user/{$folder}"],

what could be the issue here?

I was able to resolve this, I just forgot the “sites” folder. Meanwhile I enhanced the setup with help from Multisite inheritance question and see my pages. Nice.

I had to disable the email plugin, though, it failed with a composer error. But one step after the other