When switching the interface language on any topic while logged in as admin, a permanent error message appears: “Failed to preview theme because it doesn’t exist, or you don’t have permission to access it.” Regular users do not experience this issue. Steps to reproduce: Log in as admin Open a…

Issue resolved! It was caused by a stale ?preview_theme_id=6 parameter in the Chrome browser URL. Once removed, the error disappeared. Thank you for pointing that out!

Do you get this issue on a different browser with the same admin user?

No. Only Chrome. And this problem only appeared today. I just checked and other browsers don’t have this problem.

Do you see a ?preview_theme_id=ID in the browser’s address bar at any point? This error message is only shown if you’re previewing a theme with an incorrect ID. You likely did this at some point on this browser and that value “stuck” in the Chrome tab/window.

Erreur lors du changement de locale : le message « topic doesn't exist » apparaît sur tous les topics

Soutien

Denis_Kovalenko (Don't worry - Be happy) Avril 16, 2026, 2:58 5

Problème résolu ! Il était causé par un paramètre obsolète ?preview_theme_id=6 dans l’URL du navigateur Chrome. Une fois supprimé, l’erreur a disparu. Merci de l’avoir signalé !

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Erreur lors du changement de locale : le message « topic doesn't exist » apparaît sur tous les topics

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