service unavailable page when changing user client information

Chelf

When we try to modify client user information (name, email, phone,..) on users -> user management -> XXX user -> click on name user of name field, give this error:
Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Also, if i click on suggested result on search box on user management, return same error.

Osticket information:
Server Information
osTicket Version v1.15.4 (6bd7884) — Up to date
Web Server Software Apache
MySQL Version 10.1.48
PHP Version 7.4.24

PHP error log:
[proxy_fcgi:error] [client XX.XX.XX.XX:58698] AH01067: Failed to read FastCGI header, referer: https://XXXXXX/scp/users.php?id=273
[proxy_fcgi:error] (104)Connection reset by peer: [client XX.XX.XX.XX:58698] AH01075: Error dispatching request to : , referer: https://XXXXXX/scp/users.php?id=273

This error happens on this browsers: google chrome, Safari and microsoft edge by chromium.

Can give me son guidelines to resolve this?
Thanks

KevinTheJedi

@Chelf

You will need to check all error logs (general server logs, webserver error logs, PHP error logs, MySQL/MariaDB error logs, osTicket System Logs, Browser Console logs, etc.) for any related errors.

Cheers.