Fehler bei Aktualisierung auf 4.12.0-RC1

[peter.fl]

Guten Tag

Eben habe ich eine Testseite von 4.11.5 auf 4.12.0-RC1 geupdatet. Gemäss Anleitung bei der Datenbanaktualisierung habe ich die bislang nicht vorhandene Datei config/config.yml erstellt. Mit folgendem Inhalt:

doctrine:
  dbal:
    connections:
      default:
        options:
          1002: "SET SESSION sql_mode=(SELECT CONCAT(@@sql_mode, ',TRADITIONAL'))"

Anschliessend habe ich via Manager alle Caches geleert/aktualisiert.

Beim Aufruf der Seite wird diese dargestellt. Aber am Fuss erscheint das Contao-Fenster "An Error occured".

Im BE wird unten links Version 4.12.0.-RC1 angezeigt.

In var/logs finde ich als neuste Einträge Folgendes:

[2021-07-15T08:45:59.307228+02:00] security.INFO: Populated the TokenStorage with an anonymous Token. [] []
[2021-07-15T08:45:59.364216+02:00] request.CRITICAL: Uncaught PHP Exception TypeError: "strncmp() expects parameter 2 to be string, int given" at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php line 248 {"exception":"[object] (TypeError(code: 0): strncmp() expects parameter 2 to be string, int given at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php:248)"} []
[2021-07-15T08:46:02.088670+02:00] request.INFO: Matched route "tl_page.2". {"route":"tl_page.2","route_parameters":{"_token_check":true,"_controller":"Contao\\FrontendIndex::renderPage","_scope":"frontend","_locale":"de","_format":"html","parameters":"","pageModel":{"Contao\\PageModel":[]},"_route":"tl_page.2","_route_object":{"Contao\\CoreBundle\\Routing\\Page\\PageRoute":[]}},"request_uri":"https://www.variante-3.xxx.ch/hier-gehts-los.html","method":"GET"} []
[2021-07-15T08:46:02.093133+02:00] security.INFO: Populated the TokenStorage with an anonymous Token. [] []
[2021-07-15T08:46:02.114652+02:00] request.CRITICAL: Uncaught PHP Exception TypeError: "strncmp() expects parameter 2 to be string, int given" at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php line 248 {"exception":"[object] (TypeError(code: 0): strncmp() expects parameter 2 to be string, int given at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php:248)"} []
[2021-07-15T08:46:28.620485+02:00] request.INFO: Matched route "tl_page.3". {"route":"tl_page.3","route_parameters":{"_token_check":true,"_controller":"Contao\\FrontendIndex::renderPage","_scope":"frontend","_locale":"de","_format":"html","parameters":"","pageModel":{"Contao\\PageModel":[]},"_route":"tl_page.3","_route_object":{"Contao\\CoreBundle\\Routing\\Page\\PageRoute":[]}},"request_uri":"https://www.variante-3.xxx.ch/seite-1.html","method":"GET"} []
[2021-07-15T08:46:28.624684+02:00] security.INFO: Populated the TokenStorage with an anonymous Token. [] []
[2021-07-15T08:46:28.648086+02:00] request.CRITICAL: Uncaught PHP Exception TypeError: "strncmp() expects parameter 2 to be string, int given" at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php line 248 {"exception":"[object] (TypeError(code: 0): strncmp() expects parameter 2 to be string, int given at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php:248)"} []
[2021-07-15T08:46:35.722160+02:00] request.INFO: Matched route "tl_page.2". {"route":"tl_page.2","route_parameters":{"_token_check":true,"_controller":"Contao\\FrontendIndex::renderPage","_scope":"frontend","_locale":"de","_format":"html","parameters":"","pageModel":{"Contao\\PageModel":[]},"_route":"tl_page.2","_route_object":{"Contao\\CoreBundle\\Routing\\Page\\PageRoute":[]}},"request_uri":"https://www.variante-3.xxx.ch/hier-gehts-los.html","method":"GET"} []
[2021-07-15T08:46:35.726014+02:00] security.INFO: Populated the TokenStorage with an anonymous Token. [] []
[2021-07-15T08:46:35.746162+02:00] request.CRITICAL: Uncaught PHP Exception TypeError: "strncmp() expects parameter 2 to be string, int given" at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php line 248 {"exception":"[object] (TypeError(code: 0): strncmp() expects parameter 2 to be string, int given at /home/xxx/www/variante-3.xxx.ch/vendor/contao/core-bundle/src/Search/Document.php:248)"} []

PHP-Version: 7.4.21

Was will mir diese Meldung sagen, was ich tun muss, oder nicht hätte tun sollen?