Unable to log in after update from UI configured in French (3.8.16)

[sgalvagno]

Description

My UI was configured in French with version 3.6.12 before I updated to version 3.8.16. After the update, I was no longer able to log in.

I added

define('LANGUAGE_AUTO_UPDATE', 0);

in the 3.7-RC2 config file, and that allowed me to log in again.

However, once logged in, if I try to change the language in the UI, I get logged out. Strangely, when set to French, the UI remains, and I can log in. But switching to English causes a logout, though I can log in again afterward.

Steps to reproduce

1. Have the UI language configured in French (version 3.6.12).
2. Update phpList to version 3.8.16.
3. Attempt to log in (will fail).
4. Add define('LANGUAGE_AUTO_UPDATE', 0); in 3.7-RC2 config.
5. Log in successfully.
6. Try to change UI language to English and observe logout.
7. Logging in again is possible.

Questions

Is this issue known and being addressed?

Will there be an official update path from this RC or current version to stable for the database?

Are there any recommendations to avoid logout when switching UI language?

Thank you for your support.