SDCs with valid Twig syntax but printing `type: json` result in a fatal error: "Bubbling failed" in Drupal core's `Renderer` (#3546249) · Issues · project / canvas

SDCs with valid Twig syntax but printing `type: json` result in a fatal error: "Bubbling failed" in Drupal core's `Renderer`

>>> [!note] Migrated issue   Reported by: [mherchel](https://www.drupal.org/user/118428) Related to !183 >>> <h3 id="overview">Overview</h3> I'm getting an error "An unexpected error has occurred while fetching components. Error 500: Bubbling failed." when in the editor and trying to load components. I cannot recover from this. I've tried <ul> <li>Clearing cache</li> <li>Creating a new Canvas page</li> </ul> I haven't changed any code. However I did this (not sure how), I did it via the UI... but I do not have the exact steps I took to get to this error. <img src="https://www.drupal.org/files/issues/2025-09-11/Drupal_Canvas_.png" alt> Here's the stack trace from watchdog: <pre>AssertionError: Bubbling failed. in assert() (line 623 of /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php).</pre><pre>#0 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(623): assert() #1 /var/www/html/web/modules/contrib/canvas/src/Element/RenderSafeComponentContainer.php(59): Drupal\Core\Render\Renderer->executeInRenderContext() #2 [internal function]: Drupal\canvas\Element\RenderSafeComponentContainer->renderComponent() #3 /var/www/html/web/core/lib/Drupal/Core/Security/DoTrustedCallbackTrait.php(107): call_user_func_array() #4 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(871): Drupal\Core\Render\Renderer->doTrustedCallback() #5 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(433): Drupal\Core\Render\Renderer->doCallback() #6 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(245): Drupal\Core\Render\Renderer->doRender() #7 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(141): Drupal\Core\Render\Renderer->doRenderRoot() #8 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(622): Drupal\Core\Render\Renderer->Drupal\Core\Render\{closure}() #9 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(140): Drupal\Core\Render\Renderer->executeInRenderContext() #10 /var/www/html/web/modules/contrib/canvas/src/ClientSideRepresentation.php(52): Drupal\Core\Render\Renderer->renderInIsolation() #11 /var/www/html/web/modules/contrib/canvas/src/Controller/ApiConfigControllers.php(231): Drupal\canvas\ClientSideRepresentation->renderPreviewIfAny() #12 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(622): Drupal\canvas\Controller\ApiConfigControllers->Drupal\canvas\Controller\{closure}() #13 /var/www/html/web/modules/contrib/canvas/src/Controller/ApiConfigControllers.php(229): Drupal\Core\Render\Renderer->executeInRenderContext() #14 /var/www/html/web/modules/contrib/canvas/src/Controller/ApiConfigControllers.php(241): Drupal\canvas\Controller\ApiConfigControllers->Drupal\canvas\Controller\{closure}() #15 /var/www/html/web/modules/contrib/canvas/src/Controller/ApiConfigControllers.php(99): Drupal\canvas\Controller\ApiConfigControllers->normalize() #16 [internal function]: Drupal\canvas\Controller\ApiConfigControllers->list() #17 /var/www/html/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array() #18 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(622): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #19 /var/www/html/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(121): Drupal\Core\Render\Renderer->executeInRenderContext() #20 /var/www/html/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() #21 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(183): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #22 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw() #23 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Symfony\Component\HttpKernel\HttpKernel->handle() #24 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle() #25 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle() #26 /var/www/html/web/core/modules/big_pipe/src/StackMiddleware/ContentLength.php(32): Drupal\Core\StackMiddleware\ContentLength->handle() #27 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(116): Drupal\big_pipe\StackMiddleware\ContentLength->handle() #28 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(90): Drupal\page_cache\StackMiddleware\PageCache->pass() #29 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle() #30 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() #31 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(53): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() #32 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle() #33 /var/www/html/web/core/lib/Drupal/Core/DrupalKernel.php(715): Drupal\Core\StackMiddleware\StackedHttpKernel->handle() #34 /var/www/html/web/index.php(19): Drupal\Core\DrupalKernel->handle() #35 {main}</pre><h3 id="proposed-resolution">Proposed resolution</h3> Show me the components!! <h3 id="ui-changes">User interface changes</h3> > Related issue: [Issue #3522342](https://www.drupal.org/node/3522342)

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