Issue #3145563 by Charlie ChX Negyesi, NigelCunningham, alexpott, joachim,...

   * {@inheritdoc}

   */

  public function matchRequest(Request $request) {

    try {

      $collection = $this->getInitialRouteCollection($request);

    }

    // PHP 7.4 introduces changes to its serialization format, which mean that

    // older versions of PHP are unable to unserialize data that is serialized

    // in PHP 7.4. If the site's version of PHP has been downgraded, then

    // attempting to unserialize routes from the database will fail, and so the

    // router needs to be rebuilt on the current PHP version.

    // See https://www.php.net/manual/en/migration74.incompatible.php.

    catch (\TypeError $e) {

      \Drupal::service('router.builder')->rebuild();

      $collection = $this->getInitialRouteCollection($request);

    }

    if ($collection->count() === 0) {

      throw new ResourceNotFoundException(sprintf('No routes found for "%s".', $this->currentPath->getPath()));

    }