503 BeforeContainerPreviewIsRenderedEvent::__construct()

[xperseguers]

In case that's worth it, and I've seen you just released a new version (3.2.1) yesterday. I experienced a crash in some cases:

B13\Container\Events\BeforeContainerPreviewIsRenderedEvent::__construct(): Argument #4 ($item) must be of type
TYPO3\CMS\Backend\View\BackendLayout\Grid\GridColumnItem, false given, called in /srv/site/home/vendor/b13/container/Classes/Backend/Preview/GridRenderer.php on line 118

This is a TYPO3 v12 install.

I fixed/prevented it with that patch:

--- Classes/Backend/Preview/GridRenderer.bak.php	2026-01-29 16:30:36
+++ Classes/Backend/Preview/GridRenderer.php	2026-01-29 16:30:57
@@ -115,8 +115,10 @@
         if ((GeneralUtility::makeInstance(Typo3Version::class))->getMajorVersion() <= 13) {
             // cannot be used for v14 / dev-main branch
             // needs adaption in next major version
-            $beforeContainerPreviewIsRendered = new BeforeContainerPreviewIsRenderedEvent($container, $view, $grid, $parentGridColumnItem);
-            $this->eventDispatcher->dispatch($beforeContainerPreviewIsRendered);
+            if ($parentGridColumnItem instanceof ContainerGridColumnItem) {
+                $beforeContainerPreviewIsRendered = new BeforeContainerPreviewIsRenderedEvent($container, $view, $grid, $parentGridColumnItem);
+                $this->eventDispatcher->dispatch($beforeContainerPreviewIsRendered);
+            }
         }
         $rendered = $view->render();
         return $rendered;

[achimfritz]

Hi @xperseguers , can you give more details, when this happens?, and how i can reproduce it?

[xperseguers]

Using module Web > Page on the homepage of one of my numerous websites. Here are the 3 CEs on one of those homepages, nothing fancy:

In that case, only the first CE is a custom (EXT:container) CE.

[xperseguers]

I didn't investigate much more than adding the check I suggested. I didn't change my containers for a long time, but I recently upgraded like that, if that helps:

-               "b13/container": "^2.3",
-               "ichhabrecht/content-defender": "^3.2",
+               "b13/container": "^3.2",
+               "ichhabrecht/content-defender": "^3.5",

and the change seems to be related to that upgrade. I upgrade TYPO3 from v11 to v12 2 weeks before that change, thus with v2.3, but it doesn't seem to have caused any issue.

[achimfritz]

Hi @xperseguers , this is not helpful for me to reproduce the bug, please provide an example with a vanilla-Installation (TYPO3 + EXT:container + your configuration (or EXT:container-example), and describe exaclty where i have to click, to see the bug.
Else i cannot help you.
For me it looks like not (direct) an container bug, but some other problems with your project-setup (like conflict with other extension, or your configuration, or inconsistent db records)

[xperseguers]

What could be helpful for me is if you could explain me a bit what are those variables, what they represent in term of container record, ... so that I could nail it down.