French Language Storefront view not working after update to 2.4.6-p6

[aurel5542]

Preconditions and environment

• Magento version 2.4.6-p6
• Updated from 2.4.6-p3 to -> p4 -> p5 -> p6 (so I dont know which of those patches is responsible)

Steps to reproduce

Create french store view on 2.4.6-p6 - (maybe: have a theme which has "$welcomeMessage = $block->getWelcome();" in header) and change to the french language in frontend

Expected result

French store view is visible

Actual result

Blank site with writing "An error has happened during application run. See exception log for details."

In exeption.log:
main.CRITICAL: TypeError: addslashes(): Argument #1 ($string) must be of type string, null given in /vendor/magento/framework/Escaper.php:440
Stack trace:
#0 /vendor/magento/framework/Escaper.php(440): addslashes()
#1 /vendor/magento/module-theme/Block/Html/Header.php(62): Magento\Framework\Escaper->escapeQuote()
#2 /app/design/frontend/theme/theme/Magento_Theme/templates/html/header-style/header-1.phtml(3): Magento\Theme\Block\Html\Header->getWelcome()
#3 /app/design/frontend/theme/theme/Magento_Theme/templates/html/header.phtml(16): include('/home/xxxx/ma...')
#4 /vendor/magento/framework/View/TemplateEngine/Php.php(71): include('/home/theme/ma...')
#5 /vendor/magento/framework/View/Element/Template.php(263): Magento\Framework\View\TemplateEngine\Php->render()
#6 /vendor/magento/framework/View/Element/Template.php(293): Magento\Framework\View\Element\Template->fetchView()
#7 /vendor/magento/framework/View/Element/AbstractBlock.php(1128): Magento\Framework\View\Element\Template->_toHtml()
#8 /vendor/magento/framework/View/Element/AbstractBlock.php(1132): Magento\Framework\View\Element\AbstractBlock->Magento\Framework\View\Element{closure}()
#9 /vendor/magento/framework/View/Element/AbstractBlock.php(676): Magento\Framework\View\Element\AbstractBlock->_loadCache()
#10 /vendor/magento/framework/View/Layout.php(578): Magento\Framework\View\Element\AbstractBlock->toHtml()
#11 /vendor/magento/framework/View/Layout.php(555): Magento\Framework\View\Layout->_renderBlock()
#12 /vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement()
#13 /vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement()
#14 /vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer()
#15 /vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement()
#16 /vendor/magento/framework/View/Layout.php(606): Magento\Framework\View\Layout->renderElement()
#17 /vendor/magento/framework/View/Layout.php(557): Magento\Framework\View\Layout->_renderContainer()
#18 /vendor/magento/framework/View/Layout.php(510): Magento\Framework\View\Layout->renderNonCachedElement()
#19 /vendor/magento/framework/View/Layout.php(975): Magento\Framework\View\Layout->renderElement()
#20 /vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\View\Layout->getOutput()
#21 /vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\View\Layout\Interceptor->___callParent()
#22 /vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\View\Layout\Interceptor->Magento\Framework\Interception{closure}()
#23 /generated/code/Magento/Framework/View/Layout/Interceptor.php(41): Magento\Framework\View\Layout\Interceptor->___callPlugins()
#24 /vendor/magento/framework/View/Result/Page.php(260): Magento\Framework\View\Layout\Interceptor->getOutput()
#25 /vendor/magento/framework/View/Result/Layout.php(171): Magento\Framework\View\Result\Page->render()
#26 /vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\View\Result\Layout->renderResult()
#27 /vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\View\Result\Page\Interceptor->___callParent()
#28 /vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\View\Result\Page\Interceptor->Magento\Framework\Interception{closure}()
#29 /generated/code/Magento/Framework/View/Result/Page/Interceptor.php(41): Magento\Framework\View\Result\Page\Interceptor->___callPlugins()
#30 /vendor/magento/framework/App/Http.php(120): Magento\Framework\View\Result\Page\Interceptor->renderResult()
#31 /generated/code/Magento/Framework/App/Http/Interceptor.php(23): Magento\Framework\App\Http->launch()
#32 /vendor/magento/framework/App/Bootstrap.php(264): Magento\Framework\App\Http\Interceptor->launch()
#33 /pub/index.php(30): Magento\Framework\App\Bootstrap->run()
#34 {main} {"exception":"[object] (TypeError(code: 0): addslashes(): Argument #1 ($string) must be of type string, null given at /vendor/magento/framework/Escaper.php:440)"} []

I remember there was once a problem due to the french language using " ' " but it was fixed and everything worked. But not since I upgraded it does not work again. Is there any fix?
Thank you

Additional information

No response

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @aurel5542. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, Add a comment to the issue:

• @magento give me 2.4-develop instance - upcoming 2.4.x release
• For more details, review the Magento Contributor Assistant documentation.
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[aurel5542]

Hello, I dont know why but only in french store view the value for welcome message was empty after update (before it worked). I changed it (needed to flush and clear all caches first) and entered some value. Now its working.