var_export() does not handle circular references [#3267110] | Drupal.org

var_export() does not handle circular references [#3267110] | Drupal.org
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var_export() does not handle circular references
Closed (fixed)
Project:
Examples for Developers
Version:
4.0.x-dev
Component:
Code
Priority:
Normal
Category:
Bug report
Assigned:
Unassigned
Reporter:
jmohino
Created:
1 Mar 2022 at 10:48 UTC
Updated:
21 Apr 2026 at 10:35 UTC
Jump to comment:
Most recent
Problem/Motivation
I have a Drupal 9.3 site with php 7.3. After enabling the render-example module I try to go to the link "Demonstration of render array usage." and I receive an error "502 Proxy Error", in the log messages I have many warnings with the following content:
Warning: var_export does not handle circular references en Drupal\Component\Utility\Variable::export() (línea 88 de /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php)
#0 /var/www/html/my-site/web/core/includes/bootstrap.inc(346): _drupal_error_handler_real(2, 'var_export does...', '/var/www/html/m...', 88)
#1 [internal function]: _drupal_error_handler(2, 'var_export does...', '/var/www/html/m...', 88, Array)
#2 /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php(88): var_export(Object(Drupal\Core\StringTranslation\TranslatableMarkup), true)
#3 /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php(60): Drupal\Component\Utility\Variable::export(Object(Drupal\Core\StringTranslation\TranslatableMarkup), ' ', false)
#4 /var/www/html/my-site/web/modules/contrib/examples/modules/render_example/src/Controller/RenderExampleController.php(407): Drupal\Component\Utility\Variable::export(Array)
#5 [internal function]: Drupal\render_example\Controller\RenderExampleController->arrays()
#6 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#7 /var/www/html/my-site/web/core/lib/Drupal/Core/Render/Renderer.php(564): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#8 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#9 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#10 /var/www/html/my-site/vendor/symfony/http-kernel/HttpKernel.php(158): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#11 /var/www/html/my-site/vendor/symfony/http-kernel/HttpKernel.php(80): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#12 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/Session.php(58): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#13 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#14 /var/www/html/my-site/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#15 /var/www/html/my-site/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#16 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#17 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#18 /var/www/html/my-site/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /var/www/html/my-site/web/core/lib/Drupal/Core/DrupalKernel.php(708): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /var/www/html/my-site/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#21 {main}
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Issue fork
examples-3267110
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3267110-fix-the-code-to-export-variables
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Comments
Comment
#1
1 March 2022 at 10:48
jmohino
created an issue. See
original summary
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Comment
#2
jmohino
commented
11 March 2022 at 11:43
I don't know much about this, but after changing line 407 of the RenderExampleController.php file in the render_example/src/Controller folder it worked and I can see the output. Also for the 'unrendered'
Change:
'#markup' => htmlentities(Variable::export($build[$key])),
by:
'#markup' => htmlentities(json_encode($build[$key])),
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Comment
#3
jmohino
commented
11 March 2022 at 13:03
Issue summary:
View changes
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Comment
#4
jungle
He/Him
Chongqing, China
commented
19 February 2023 at 05:23
Version:
3.0.3
» 4.0.x-dev
Status:
Active
» Postponed (maintainer needs more info)
You can always use
dpm()
with the Devel module installed for debugging.
Would you try it with the latest dev branch 4.0.x (for Drupal core 9.4+) or the latest release 4.0.0 to see if the bug still exists?
Thanks!
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Comment
#5
optlai
commented
23 April 2024 at 07:38
yes bug still exist.
Drupal 10.2.5 + version 4.0.2
I have Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 534777856 bytes) in /app/web/core/lib/Drupal/Component/Utility/Variable.php on line 88
with '#markup' => htmlentities(json_encode($build[$key])), no problem
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#6
avpaderno
he/him
Italian
Brescia, 🇮🇹 🇪🇺
commented
27 June 2024 at 19:41
I think that what described here explains why adding
\Drupal\render_example\Controller\RenderExampleController::preRender()
as pre-render callback causes two tests to fails.
In fact, one of the tests expects to get a 200 status back, but it gets a 500 status. Usually, that is caused by some errors on PHP side, like the one described here.
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#7
avpaderno
he/him
Italian
Brescia, 🇮🇹 🇪🇺
commented
27 June 2024 at 19:47
Title:
render-example var_export does not handle circular references
» var_export() does not handle circular references
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#8
27 June 2024 at 19:51
apaderno
opened
merge request !44
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#9
avpaderno
he/him
Italian
Brescia, 🇮🇹 🇪🇺
commented
27 June 2024 at 19:51
Status:
Postponed (maintainer needs more info)
» Needs review
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#10
avpaderno
he/him
Italian
Brescia, 🇮🇹 🇪🇺
commented
2 October 2025 at 09:28
Component:
Render Example
» Code
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Comment
#11
7 April 2026 at 10:32
avpaderno
committed
7da2ba3d
on
4.0.x
Issue #3267110: var_export() does not handle circular references
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#12
avpaderno
he/him
Italian
Brescia, 🇮🇹 🇪🇺
commented
7 April 2026 at 10:33
Status:
Needs review
» Fixed
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Comment
#13
7 April 2026 at 10:33
Now that this issue is closed,
review the
contribution record
As a contributor, attribute any organization that helped you, or if you volunteered your own time.
Maintainers, credit people who helped resolve this issue.
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Comment
#14
21 April 2026 at 10:35
Status:
Fixed
» Closed (fixed)
Automatically closed - issue fixed for 2 weeks with no activity.
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Contribution record
Add child issue
clone issue
Referenced by
#2986435: Fix the code in \Drupal\render_example\Controller\RenderExampleController::preRender()
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