Apache fails to start: mod_proxy must be loaded for mod_lbmethod_bybusyness

Symptoms

• Apache fails to start with the following error in /var/log/httpd/error_log:

CONFIG_TEXT: [Tue Feb 25 17:38:57.205085 2025] [lbmethod_bybusyness:emerg] [pid 96270:tid 140387384006976] AH10151: mod_proxy must be loaded for mod_lbmethod_bybusyness
[Tue Feb 25 17:38:57.205090 2025] [:emerg] [pid 96270:tid 140387384006976] AH00020: Configuration Failed, exiting

• rpm -V shows modified binary files:

CONFIG_TEXT: # rpm -V httpd.x86_64
S.5....T. c /etc/httpd/conf.d/userdir.conf
S.5....T. c /etc/httpd/conf.modules.d/00-mpm.conf
S.5....T. c /etc/httpd/conf.modules.d/00-proxy.conf
S.5....T. c /etc/httpd/conf/httpd.conf
S.5....T. c /etc/logrotate.d/httpd
S.5....T. /usr/lib64/httpd/modules/mod_proxy.so
S.5....T. /usr/lib64/httpd/modules/mod_proxy_fcgi.so
SM5....TP /usr/sbin/suexec

• Re-installing the httpd package is not resolving the issue.

Cause

Modified mod_proxy.so file, which is not being replaced during the httpd package re-installation.

Resolution

1. Connect to the server via SSH.

2. Download the httpd package:

# dnf download httpd-2.4.37-65.module_el8.10.0+3966+b9483c84.3.x86_64

3. Extract the necessary module files:

# rpm2cpio httpd-2.4.37-65.module_el8.10.0+3966+b9483c84.3.x86_64.rpm | cpio -idmv ./etc/httpd/conf.d/userdir.conf ./etc/httpd/conf.modules.d/00-mpm.conf ./etc/httpd/conf.modules.d/00-proxy.conf ./etc/httpd/conf/httpd.conf ./etc/logrotate.d/httpd ./usr/lib64/httpd/modules/mod_proxy.so ./usr/lib64/httpd/modules/mod_proxy_fcgi.so

4. Rename the modified module files:

# mv /etc/httpd/conf.modules.d/00-mpm.conf /etc/httpd/conf.modules.d/00-mpm.conf-old

# mv /etc/httpd/conf.modules.d/00-proxy.conf /etc/httpd/conf.modules.d/00-proxy.conf-old

# mv /usr/lib64/httpd/modules/mod_proxy.so /usr/lib64/httpd/modules/mod_proxy.so-old

# mv /usr/lib64/httpd/modules/mod_proxy_fcgi.so /usr/lib64/httpd/modules/mod_proxy_fcgi.so-old

4. Move the extracted module files to the correct locations:

# mv 00-proxy.conf /etc/httpd/conf.modules.d/

# mv 00-mpm.conf /etc/httpd/conf.modules.d/

# mv mod_proxy.so /usr/lib64/httpd/modules/

# mv mod_proxy_fcgi.so /usr/lib64/httpd/modules/

5. Repair the web server configuration:

# plesk repair web -y