HTTP 400 (Bad request) on form submission

Hi there,
we have following problem with form submission (contact form), which we think might have something to do with NinjaFirewall:

We use NinjaFirewall v. 4.5.4 on WordPress 6.0.3 with Avada Theme v. 7.8.2

– When logged in as admin, the form submission works fine and the email is sent out successfully. Of course, as admin, we are whitelisted by the firewall.

– When not logged in, the form submission fails. The server log says:
Error my.ip.addr.x 400 POST /wp-admin/admin-ajax.php HTTP/1.1

There is no entry pertaining to this problem in the firewall log.

Here is the wp-check.php:

NinjaFirewall (WP edition) troubleshooter
HTTP server 	: 	Apache
PHP version 	: 	7.4.16
PHP SAPI 	: 	FPM-FCGI
 	 	 
auto_prepend_file 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content/nfwlog/ninjafirewall.php
Loader's path to firewall 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content/plugins/ninjafirewall/lib/firewall.php	
wp-config.php 	: 	found in /var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-config.php
NinjaFirewall detection 	: 	NinjaFirewall WP Edition is loaded (Full WAF mode)
 	 	 
Loaded INI file 	: 	/opt/plesk/php/7.4/etc/php.ini
user_ini.filename 	: 	.user.ini
user_ini.cache_ttl 	: 	300 seconds
User PHP INI 	: 	.user.ini found -
 	 	 
DOCUMENT_ROOT 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs
ABSPATH 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/
WordPress version 	: 	6.0.3
WP_CONTENT_DIR 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content
Plugins directory 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content/plugins
User Role 	: 	Administrator
User Capabilities 	: 	manage_options: OK - unfiltered_html: OK
Log dir permissions 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content/nfwlog dir is writable
Cache dir permissions 	: 	/var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-content/nfwlog/cache dir is writable

NinjaFirewall (WP edition) troubleshooter v1.9.4

And the wp-db.php:

Version: 2.0.2
Found .htninja file, parsing it.
Found /var/www/vhosts/my-anonymized-domain.de/httpdocs/wp-config.php.
Opening it for reading.
Looking for DB_NAME, DB_USER, DB_PASSWORD, DB_HOST and $table_prefix:
DB_NAME: found 'anonymized_db'
DB_USER: found 'anonymized_dbusr'
DB_PASSWORD: found (click here to view password)
DB_HOST: found 'ano.ny.mi.zed'
table_prefix: found 'wp_'
Attempting to connect to the DB: OK

Attempting to read NinjaFirewall's options (nfw_options) from the DB: OK
Calling fetch_object: OK
Checking options integrity: OK

Attempting to read NinjaFirewall's rules (nfw_rules) from the DB: OK
Calling fetch_object: OK
Checking rules integrity: OK
Exiting.

The .htninja just whitelists the server on which the website is running.

Thanks for any helpful advice.
Best,
Larry

• This topic was modified 37 minutes ago by gwdlarry.
• This topic was modified 35 minutes ago by gwdlarry.