Issue undefined symbol: ap_proxy_check_connection

[Konggal]

Hello today my server went a bit haywire and out of the blue started to fail restarting the apache2 server due to proxy-fcgi module
Looked around with google and found that the load order was messed up and it didn't load proxy_module first which is proxy.load so added that to the apache2.conf with

LoadModule proxy_module /usr/lib/apache2/modules/mod_proxy.so

To make sure it would be loaded before it tried to load proxy-fcgi.load which worked
but now it gives me this error and there isn't anything on google about the error other than 1 serverfault.com post which they are just saying to open a ticket with "undefined symbol: ap_proxy_check_connection"

apache2: Syntax error on line 144 of /etc/apache2/apache2.conf: Syntax error on line 2 of /etc/apache2/mods-enabled/proxy-fcgi.load: Cannot load /usr/lib/apache2/modules/mod_proxy_fcgi.so into server: /usr/lib/apache2/modules/mod_proxy_fcgi.so: undefined symbol: ap_proxy_check_connection

Running Plesk Onyx Version 17.5.3 Update #35
on Debian 8.10 with apache/2.4.29

Also if PHP support is set to run PHP as FPM application served by apache while the proxy-fcgi is disabled it just downloads the url instead of opening it as soon as it changed to FastCGI application served by apache then it loads the pages fine without just downloading them

 

[newbob23]

Had the same isssue with the following setup:

Plesk Onyx Version 17.8.8
‪Debian 9.3‬
Apache/2.4.25

These steps solved the problem on my system:

1. Purging an outdated libapache2-mod-proxy-psa (initially installed while using Debian 8.x)
2. Disabling the Apache modules proxy_fcgi and proxy
3. Re-enabling the Apache modules proxy_fcgi and proxy
4. Restarting Apache

 

[Konggal]

Had the same isssue with the following setup:

Plesk Onyx Version 17.8.8
‪Debian 9.3‬
Apache/2.4.25

These steps solved the problem on my system:

1. Purging an outdated libapache2-mod-proxy-psa (initially installed while using Debian 8.x)
2. Disabling the Apache modules proxy_fcgi and proxy
3. Re-enabling the Apache modules proxy_fcgi and proxy
4. Restarting Apache

Purge as in uninstall or just update?

 

[newbob23]

I've removed the package via
aptitude purge libapache2-mod-proxy-psa

I didn't get any dependency warnings but keep this in mind and make sure that no other (used) packages will be removed.

 

[Konggal]

Tried and no luck :/

Hope one of the plesk guys comes by or someone who have any idea how to fix it :/
Kinda scared I'm facing a total reinstall :/

 

[Konggal]

Is it possible to reinstall apache2 + all the modules completely with plesk without messing plesk up?

 

[newbob23]

Reinstalling apache and its modules shouldn't be problem. Have you doublechecked that there aren't any outdated modules installed/active?
You should use proxy_fcgi and proxy from the same Debian repository / version as apache.