Hi Ivo,

For my project, I followed the Joomla documentation in order to make my website bilangual, English and Dutch.
That works perfectly in combination with IT templates.

However, the 404 page has some strange things:

both the Dutch and English versions of this 404 page show the English menu.

That is not a big problem, this would be good enough, except... the Dutch 404 page doesn't show the regular menu items in the Construction template:
it only shows the Contacts particles, like the phone number in the demo. Because that particles use a link in my case, with an English alias (because it's the English menu), it gives another 404 when you click it (because the link will be: /nl/english-alias).

When you read this, do you have any idea what might cause this? I spent the afternoon trying to fix it but without luck.
I also tried to create a custom 404 page, following the Joomla documentation (creating an article and edit error.php), but this didn't work either
(in the past, I was able to do this, but that was in a Helix 3 template).

Maybe there is some difficulty in the relation 'Construction template' <> 'error.php files' <> '2 language website' <> 'Gantry 5' in some way?
I can't find a starting point to solve it. The Gantry 5 tutorial is short.
In case you might want to have a look, it is the website I sent you in a PM this week.

/test-404 is an English page, with complete English menu, which is good;
/nl/test-404 is a Dutch page, with proper Dutch translation of page not found, but with an (incomplete) English menu.

I realize that this question is another one beyond the scope of your support, no problem if you choose not to look at it!

Have a nice evening,
with kind regards,
Stefan