Topic list is displayed in German (DE) but contains one untranslated German (DE) topic

[GrahamM]

Hello,

I’m experiencing an issue with my Discourse installation regarding automatic AI translation.

Current setup:

• Automatic AI translation is enabled and generally works very well

• default locale: English

• allow user locale: enabled

Problem description:

When a user visits the forum for the first time (by directly entering the URL in the browser), the list of topics is not consistently localized:

• Some topic titles appear in the visitor’s language

• Others remain in their original language

However:

• When clicking on the forum logo (triggering an internal navigation), all topic titles are correctly translated

• When using the browser refresh button afterward, the issue reappears and translations become inconsistent again

It seems like translations are not reliably applied on initial page load or after a full page refresh, but work correctly during internal navigation.

Has anyone encountered this behavior before or has an idea what might be causing it?

Any help would be greatly appreciated.

Best regards,
M

self-hosted - Version 2026.4.0-latest

[GrahamM]

After further investigation, I noticed a clear pattern:

• If a visitor e.g. has German as their browser language:

  • Topic titles originally written in other languages are correctly translated into German

  • However, topic titles that were originally written in German are displayed in English (the forum’s default language)

This behavior can be reproduced with other browser languages as well:

• The visitor language is applied partially

• But content that already matches the visitor language seems to fall back to the default forum language instead

Strange…

[nat (Natalie T)]

Can you confirm you have these settings?

@nat

• Content localization enabled is

• Allow user locale is (enabled by default)
• Set locale from cookie is

And German is in your list of supported languages? If the user is seeing partial translations, it could be that backfill is too slow.

There’s also this setting:

• Content localization use default locale when unsupported

[Moin]

Great that you were able to narrow down the problem! I can reproduce that here on Meta (private browser window, logged out).
The only topic shown in English is 🇩🇪 Fehler in der Deutschen Übersetzung? Hier melden!

@nat it’s not mixed because of missing translations, but the topic which was written in German is shown in English while all the other topics are in German as expected.

[GrahamM]

Content localization enabled:
Allow user locale:
Set locale from cookie:
And German is in your list of supported languages:

If the user is seeing partial translations, it could be that backfill is too slow

All topics are fully translated

It is reproducible with other (supported) languages.

[nat (Natalie T)]

Oh interesting. Having a look.

[GrahamM]

Hi there,

indeed, the issue is also present here in the meta It shows exactly the same behavior as in my forum.

@nat Here’s a video about the issue

This problem has existed for some time. I thought it was due to my settings.