Please help us help you and fill where relevant:
LimeSurvey version: 6.17.13+260728
Own server or LimeSurvey Cloud: Own server
Survey theme/template:
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Hello,

We upgraded our LimeSurvey installation from 6.10.5 to 6.17.13+260728.

The database upgrade completed successfully and the current database version is:

DBVersion = 651

Since the upgrade, all users receive the following popup message every time they log in:

"The allowed hosts file (application/config/allowed_hosts.php) could not be created because the application/config directory is not writable."

Environment:
- LimeSurvey version: 6.17.13+260728
- Database version: 651
- Database: MySQL 8.0.29 Enterprise
- PHP: 8.3.31
- Operating System: RHEL Red Hat Enterprise Linux release 9.8 (Plow)
- Two application servers behind an F5 load balancer

Verification performed:
- application/config is writable by the web server user.
- We successfully created a test file in application/config as the Apache user.
- SELinux contexts appear correct.
- The application is otherwise fully functional.
- application/config/allowed_hosts.php does not exist.
- The popup is displayed on every login.

Question:
Is allowed_hosts.php expected to be created automatically in LimeSurvey 6.17.13?

If so, under what conditions is the file generated?

Could this warning be a false positive even when application/config is writable?

We reviewed issue #20560 regarding automatic creation of allowed_hosts.php and would like to understand whether the current behavior is expected in 6.17.13.

Thank you.
Young