Error 404 when user changes current Language in Category or Product Page

[extonjaez]

Hello

In my site, when an user is in a english category/product page and clicks in the french flag (to go to french category/product page), a 404 error is displayed.

English Category page -> French Category page (by clicking French flag)
https://la-vie.paris/en/some-links/manufacturer/grand-paris

English product page -> French product page (by clicking French flag)
https://la-vie.paris/en/some-links/orsay-museum-detail

Do you know why ? 
Many Thanks
Arnaud

System Information
VirtueMart 4.2.2 10908
PHP Built On   Linux s22095112 4.19.0-17-amd64 #1 SMP Debian 4.19.194-2 (2021-06-21) x86_64
Database Type   mysql
Database Version   10.3.39-MariaDB-0+deb10u1
Database Collation   utf8mb4_general_ci
Database Connection Collation   utf8mb4_general_ci
PHP Version   8.1.22
Web Server   Apache
WebServer to PHP Interface   cgi-fcgi
Joomla! Version   Joomla! 4.3.4 Stable [ Bora ] 22-August-2023 16:00 GMT
User Agent   Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

[ViPeS]

In my site, when an user is in a english category/product page and clicks in the french flag (to go to french category/product page), a 404 error is displayed.

English Category page -> French Category page (by clicking French flag)
https://la-vie.paris/en/some-links/manufacturer/grand-paris

Do you know why ? 

404 error appears because the page is opening https://la-vie.paris/fr/exemples-de-liens/manufacturer/grand-paris does not exist.
Is there such a page https://la-vie.paris/fr/exemples-de-liens/fournisseur/paris-et-villes-proches

You are using Language Switcher Joomla Core, it must be configured correctly.

[extonjaez]

404 error appears because the page is opening https://la-vie.paris/fr/exemples-de-liens/manufacturer/grand-paris does not exist.
Is there such a page https://la-vie.paris/fr/exemples-de-liens/fournisseur/paris-et-villes-proches

You are using Language Switcher Joomla Core, it must be configured correctly.

We are not hardcoding the links, VM SEF creates the links. You can see that the product links also result in 404 when switching the language.
VM is not simply not creating correct links for other languages but the active one.

[extonjaez]

Some Help please...
Many Thanksss 

[extonjaez]

............

[Milbo]

Do you use the language module of the membership? or the one of joomla?

[extonjaez]

Do you use the language module of the membership? or the one of joomla?

Hello Milbo!!

Thanks for your anwser 
What do you mean by module of the membership (do you mean "Shop Language Switcher for VM" by Studio 42) ?
I use "Language Switcher Site" Module from Joomla! Project...

Best Regards
Arnaud
Modify message

[extonjaez]

Some Help please 

[Milbo]

You are using the Language switcher of the joomla project and you get this error? That is strange. There is an extra language switcher for members. Did you try that one?