'Attempt to read property "childNodes" on null' and some Symphony error messages

Hi
I have pages behind login, and I got it working as suggested here

by initiating the session in sitecake.php.

But now when I try to login to Sitecake, the login is not accepted but I receive these errors in Apache error log:

[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Symfony\Component\Routing\Route implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary) in /mysite/sitecake/2.5.0/vendor/symfony/routing/Route.php on line 20
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Silex\Route implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary) in /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Route.php on line 21
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\Routing\RouteCollection::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/routing/RouteCollection.php on line 54
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\Routing\RouteCollection::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/routing/RouteCollection.php on line 64
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Sitecake\Util\ObjectRegistry::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/src/Sitecake/Util/ObjectRegistry.php on line 326
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Sitecake\Util\ObjectRegistry::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/src/Sitecake/Util/ObjectRegistry.php on line 316
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\HttpFoundation\ParameterBag::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/http-foundation/ParameterBag.php on line 220
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\HttpFoundation\ParameterBag::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/http-foundation/ParameterBag.php on line 230
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\HttpFoundation\HeaderBag::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/http-foundation/HeaderBag.php on line 288
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: Return type of Symfony\Component\HttpFoundation\HeaderBag::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /mysite/sitecake/2.5.0/vendor/symfony/http-foundation/HeaderBag.php on line 298
[03-Oct-2024 10:06:43 UTC] PHP Deprecated: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /mysite/sitecake/2.5.0/vendor/symfony/http-foundation/Request.php on line 316

In the subfolder of sitecake-temp/ in the log/sitecake.log I see these messages:

[2024-10-03 10:06:44] app.WARNING: Warning (2): Attempt to read property “childNodes” on null in [/mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php, line 478] Stack Trace: #0 /mysite/sitecake/2.5.0/src/Sitecake/Error/ErrorHandler.php(364): Sitecake\Error\ErrorHandler->logError() #1 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(478): Sitecake\Error\ErrorHandler->handleError() #2 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(405): Sitecake\Content\Element->createDOM() #3 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(200): Sitecake\Content\Element->append() #4 /mysite/sitecake/2.5.0/src/Sitecake/Content/DOM/HTMLManipulationTrait.php(125): Sitecake\Content\Element->html() #5 /mysite/sitecake/2.5.0/src/Sitecake/Content/ContentManagerAwareTrait.php(62): Sitecake\Content\ContentManager->appendTo() #6 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(171): Sitecake\PageManager\Page->appendTo() #7 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(41): Sitecake\Services\SessionService->ensureMetaTag() #8 /mysite/sitecake/2.5.0/src/Sitecake/Services/SessionService.php(128): Sitecake\Services\SessionService->preparePageForRender() #9 /mysite/sitecake/2.5.0/src/Sitecake/Services/Service.php(135): Sitecake\Services\SessionService->login() #10 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(135): Sitecake\Services\Service->invokeAction() #11 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(109): Sitecake\ActionDispatcher->invoke() #12 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(539): Sitecake\ActionDispatcher->dispatch() #13 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(517): Sitecake\Sitecake->handleRequest() #14 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(151): Sitecake\Sitecake->Sitecake{closure}() #15 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw() #16 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(496): Symfony\Component\HttpKernel\HttpKernel->handle() #17 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(477): Silex\Application->handle() #18 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(505): Silex\Application->run() #19 /mysite/sitecake/2.5.0/src/app.php(16): Sitecake\Sitecake->run() #20 /mysite/sitecake.php(1): require(’…’) [] []
[2024-10-03 10:06:44] app.WARNING: Warning (2): foreach() argument must be of type array|object, null given in [/mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php, line 407] Stack Trace: #0 /mysite/sitecake/2.5.0/src/Sitecake/Error/ErrorHandler.php(364): Sitecake\Error\ErrorHandler->logError() #1 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(407): Sitecake\Error\ErrorHandler->handleError() #2 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(200): Sitecake\Content\Element->append() #3 /mysite/sitecake/2.5.0/src/Sitecake/Content/DOM/HTMLManipulationTrait.php(125): Sitecake\Content\Element->html() #4 /mysite/sitecake/2.5.0/src/Sitecake/Content/ContentManagerAwareTrait.php(62): Sitecake\Content\ContentManager->appendTo() #5 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(171): Sitecake\PageManager\Page->appendTo() #6 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(41): Sitecake\Services\SessionService->ensureMetaTag() #7 /mysite/sitecake/2.5.0/src/Sitecake/Services/SessionService.php(128): Sitecake\Services\SessionService->preparePageForRender() #8 /mysite/sitecake/2.5.0/src/Sitecake/Services/Service.php(135): Sitecake\Services\SessionService->login() #9 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(135): Sitecake\Services\Service->invokeAction() #10 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(109): Sitecake\ActionDispatcher->invoke() #11 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(539): Sitecake\ActionDispatcher->dispatch() #12 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(517): Sitecake\Sitecake->handleRequest() #13 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(151): Sitecake\Sitecake->Sitecake{closure}() #14 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw() #15 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(496): Symfony\Component\HttpKernel\HttpKernel->handle() #16 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(477): Silex\Application->handle() #17 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(505): Silex\Application->run() #18 /mysite/sitecake/2.5.0/src/app.php(16): Sitecake\Sitecake->run() #19 /mysite/sitecake.php(1): require(’…’) [] []
[2024-10-03 10:06:44] app.WARNING: Warning (2): Attempt to read property “length” on null in [/mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php, line 412] Stack Trace: #0 /mysite/sitecake/2.5.0/src/Sitecake/Error/ErrorHandler.php(364): Sitecake\Error\ErrorHandler->logError() #1 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(412): Sitecake\Error\ErrorHandler->handleError() #2 /mysite/sitecake/2.5.0/src/Sitecake/Content/Element.php(200): Sitecake\Content\Element->append() #3 /mysite/sitecake/2.5.0/src/Sitecake/Content/DOM/HTMLManipulationTrait.php(125): Sitecake\Content\Element->html() #4 /mysite/sitecake/2.5.0/src/Sitecake/Content/ContentManagerAwareTrait.php(62): Sitecake\Content\ContentManager->appendTo() #5 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(171): Sitecake\PageManager\Page->appendTo() #6 /mysite/sitecake/2.5.0/src/Sitecake/Content/PageRenderAwareTrait.php(41): Sitecake\Services\SessionService->ensureMetaTag() #7 /mysite/sitecake/2.5.0/src/Sitecake/Services/SessionService.php(128): Sitecake\Services\SessionService->preparePageForRender() #8 /mysite/sitecake/2.5.0/src/Sitecake/Services/Service.php(135): Sitecake\Services\SessionService->login() #9 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(135): Sitecake\Services\Service->invokeAction() #10 /mysite/sitecake/2.5.0/src/Sitecake/ActionDispatcher.php(109): Sitecake\ActionDispatcher->invoke() #11 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(539): Sitecake\ActionDispatcher->dispatch() #12 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(517): Sitecake\Sitecake->handleRequest() #13 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(151): Sitecake\Sitecake->Sitecake{closure}() #14 /mysite/sitecake/2.5.0/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw() #15 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(496): Symfony\Component\HttpKernel\HttpKernel->handle() #16 /mysite/sitecake/2.5.0/vendor/silex/silex/src/Silex/Application.php(477): Silex\Application->handle() #17 /mysite/sitecake/2.5.0/src/Sitecake/Sitecake.php(505): Silex\Application->run() #18 /mysite/sitecake/2.5.0/src/app.php(16): Sitecake\Sitecake->run() #19 /mysite/sitecake.php(1): require(’…’) [] []

The script /mysite/index.php does check the session, too.

What would help? Could I update the Symfony myself?