Symptoms
- Apache service fails to start with the following errors:
Can't locate API module structure `proxy.plesk_module' in file /usr/lib64/httpd/modules/mod_proxy.plesk.so: /usr/lib64/httpd/modules/mod_proxy.plesk.so: undefined symbol: proxy.plesk_module
Cannot load /usr/lib64/httpd/modules/mod_proxy_fcgi.plesk.so into server: /usr/lib64/httpd/modules/mod_proxy_fcgi.plesk.so: undefined symbol: proxy_module
Cause
Corresponding modules are present in the Apache configuration file twice under different names:
mod_proxy_fcgi.so and mod_proxy_fcgi.plesk.so
mod_proxy.so and mod_proxy.plesk.so
Resolution
1.Connect to the server via SSH
2.Find the configuration file from where these modules are loaded:
#egrep -R 'mod_proxy.plesk|mod_proxy_fcgi.plesk' /etc/httpd/
/etc/httpd/conf.modules.d/00-base.conf: LoadModule proxy.plesk_module /usr/lib64/httpd/modules/mod_proxy.plesk.so
/etc/httpd/conf.modules.d/00-base.conf: LoadModule proxy_fcgi.plesk_module /usr/lib64/httpd/modules/mod_proxy_fcgi.plesk.so
3.Edit /etc/httpd/conf.modules.d/00-base.conf and comment out above lines with a preceding "#":
#LoadModule proxy.plesk_module /usr/lib64/httpd/modules/mod_proxy.plesk.so
#LoadModule proxy_fcgi.plesk_module /usr/lib64/httpd/modules/mod_proxy_fcgi.plesk.so
4.Repair configuration files:
#plesk repair web -y
5.Start apache if required:
#service httpd start