apache2 httpd apache server will not start [pid 22449:tid 139972160445760] AH00052: child pid 23248 exit signal Aborted (6) solution Mint Debian Ubuntu Redhat

If you get this error, it is often because you have configured Apache with modules that weren't actually installed. Eg. you try to load the PHP module but didn't actually install the apache2 php module, so the server can't start. In general, this error can often be caused by issues with problematic modules and/or Apache being configured for modules that have not actually be installed (eg. libapache2-mod-php) is missing.

The above results in this less than obvious error:

[pid 22449:tid 139972160445760] AH00052: child pid 23248 exit signal Aborted (6)

Install the missing module into Apache 2 to solve it

In this test case we know the issue is PHP missing from Apache

apt install libapache2-mod-php

Of course if you were using another module, you would want to install the corresponding one.

Here is a list of apache2 modules from Debian 11:

libapache2-mod-upload-progress - upload progress support for the Apache web server libapache2-mod-md - transitional package libapache2-mod-proxy-uwsgi - transitional package libapache2-mod-xforward - Apache module implements redirection based on X-Forward response header libapache2-mod-apparmor - changehat AppArmor library as an Apache module libapache2-mod-auth-radius - Apache 2.x module for RADIUS authentication libapache2-mod-evasive - evasive module to minimize HTTP DoS or brute force attacks libapache-mod-jk-doc - Documentation of libapache2-mod-jk package libapache2-mod-jk - Apache 2 connector for the Tomcat Java servlet engine libapache2-mod-log-sql - Use SQL to store/write your Apache queries logs - Base libapache2-mod-log-sql-dbi - Use SQL to store/write your Apache queries logs - DBI interface libapache2-mod-log-sql-mysql - Use SQL to store/write your Apache queries logs - MySQL interface libapache2-mod-log-sql-ssl - Use SQL to store/write your Apache queries logs - SSL extension libapache2-mod-musicindex - Browse, stream, download and search through MP3/Ogg/FLAC files libapache2-mod-removeip - Module to remove IP from apache2's logs libapache2-authcassimple-perl - Apache2 module to authenticate trough a CAS server libapache2-authcookie-perl - Perl Authentication and Authorization via cookies libapache2-mod-auth-cas - CAS authentication module for Apache2 libapache2-mod-auth-gssapi - GSSAPI Authentication module for Apache2 libapache2-mod-auth-mellon - SAML 2.0 authentication module for Apache libapache2-mod-auth-openid - OpenID authentication module for Apache2 libapache2-mod-auth-openidc - OpenID Connect authentication module for Apache libapache2-mod-auth-plain - Module for Apache2 which provides plaintext authentication libapache2-mod-auth-pubtkt - key-based single-sign-on authentication module for Apache libapache2-mod-auth-tkt - lightweight single-sign-on authentication module for Apache libapache2-mod-authn-sasl - SASL authentication backend provider for Apache libapache2-mod-authn-yolo - Yolo style authentication for Apache 2 libapache2-mod-authn-yubikey - Yubikey authentication provider for Apache libapache2-mod-authnz-external - authenticate Apache against external authentication services libapache2-mod-authnz-pam - PAM authorization checker and PAM Basic Authentication provider libapache2-mod-authz-unixgroup - access control based on on unix group membership for Apache libapache2-mod-bw - bandwidth limiting module for apache2 libapache2-mod-defensible - module for Apache2 which provides DNSBL usage libapache2-mod-encoding - Apache2 module for non-ascii filename interoperability libapache2-mod-fcgid - FastCGI interface module for Apache 2 libapache2-mod-form - Apache module to decode data submitted from Web forms libapache2-mod-form-dev - Apache module to decode data submitted from Web forms (development files) libapache2-mod-geoip - GeoIP support for apache2 libapache2-mod-intercept-form-submit - Apache module to intercept login form submission and run PAM authentication libapache2-mod-ldap-userdir - Apache module that provides UserDir lookups via LDAP libapache2-mod-ldap-userdir-dbg - Debugging symbols for mod_ldap_userdir libapache2-mod-lisp - An Apache2 module that interfaces with Lisp environments libapache2-mod-log-slow - Apache module for logging of slow requests handling libapache2-mod-lookup-identity - Apache module to retrieve additional information about the authenticated user libapache2-mod-perl2 - Integration of perl with the Apache2 web server libapache2-mod-perl2-dev - Integration of perl with the Apache2 web server - development files libapache2-mod-perl2-doc - Integration of perl with the Apache2 web server - documentation libapache2-mod-python - Python-embedding module for Apache 2 libapache2-mod-python-doc - Python-embedding module for Apache 2 - documentation libapache2-mod-qos - quality of service module for the apache2 libapache2-mod-rivet - Server-side Tcl programming system combining ease of use and power libapache2-mod-rivet-doc - Documentation for Rivet, a server-side Tcl programming system libapache2-mod-rpaf - module for Apache2 which takes the last IP from the 'X-Forwarded-For' header libapache2-mod-tile - Apache module to deliver tiles created by renderd libapache2-mod-watchcat - Process monitoring Apache module libapache2-mod-xsendfile - Serve large static files efficiently from web applications libapache2-reload-perl - module for reloading Perl modules when changed on disk libapache2-sitecontrol-perl - perl web site authentication/authorization system libapache2-mod-apreq2 - generic Apache request library - Apache module libapache2-request-perl - generic Apache request library - Perl modules libapache2-mod-mapcache - tile caching server - Apache module libapache2-mod-dnssd - Zeroconf support for Apache 2 via avahi libapache2-mod-mime-xattr - Apache2 module to get MIME info from filesystem extended attributes libapache2-mod-mono - Apache module for running ASP.NET applications on Mono libapache2-mod-vhost-ldap - Apache 2 module for Virtual Hosting from LDAP libapache2-mod-wsgi-py3 - Python 3 WSGI adapter module for Apache libapache2-mod-security2 - Tighten web applications security for Apache libapache2-mpm-itk - multiuser module for Apache libapache2-mod-neko - Apache module for running server-side Neko programs libapache2-mod-netcgi-apache - OCaml application-level Internet libraries - netcgi2 Apache2 connector libapache2-mod-parser3 - Parser 3, HTML-embedded scripting language (Apache2 module) libapache2-mod-passenger - Rails and Rack support for Apache2 libapache2-mod-php - server-side, HTML-embedded scripting language (Apache 2 module) (default) libapache2-mod-php7.4 - server-side, HTML-embedded scripting language (Apache 2 module) libapache2-mod-r-base - server-side R integration with Apache 2 libapache2-mod-shib - Federated web single sign-on system (Apache module) libapache2-mod-svn - Apache Subversion server modules for Apache httpd libapache2-mod-ruwsgi - uwsgi module for Apache2 (mod_Ruwsgi) libapache2-mod-ruwsgi-dbg - debugging symbols for Apache2 mod_Ruwsgi libapache2-mod-uwsgi - uwsgi module for Apache2 (mod_uwsgi) libapache2-mod-uwsgi-dbg - debugging symbols for Apache2 mod_uwsgi libapache2-mod-webauth - Apache module for WebAuth authentication libapache2-mod-webauthldap - Apache module for WebAuth LDAP lookup and authorization libapache2-mod-webkdc - Apache modules for a WebAuth authentication KDC