When migrating from Apache HTTPD 2.22 to 2.24 with LDAP authentication, developers often encounter the error:

Invalid command 'AuthzLDAPAuthoritative', perhaps misspelled or defined by a module not included in the server configuration

The main breaking change is the deprecation and removal of the mod_authz_ldap module, which previously provided the AuthzLDAPAuthoritative directive. The authorization functionality has been consolidated into mod_ldap and mod_authnz_ldap.

Replace your old 2.22 configuration:

<IfModule mod_authz_ldap.c>
    AuthzLDAPAuthoritative on
</IfModule>

With this 2.24-compatible version:

LoadModule authnz_ldap_module modules/mod_authnz_ldap.so

<Location /secure>
    AuthType Basic
    AuthName "LDAP Authentication"
    AuthBasicProvider ldap
    AuthLDAPURL "ldap://ldap.example.com:389/dc=example,dc=com?uid?sub?(objectClass=*)"
    AuthLDAPBindDN "cn=admin,dc=example,dc=com"
    AuthLDAPBindPassword "secret"
    Require valid-user
</Location>

For SSO implementation, ensure you have these modules loaded:

LoadModule session_module modules/mod_session.so
LoadModule session_cookie_module modules/mod_session_cookie.so
LoadModule session_crypto_module modules/mod_session_crypto.so

Example SSO configuration:

<IfModule mod_session.c>
    Session On
    SessionCookieName session path=/
    SessionCryptoPassphrase "your-secret-passphrase"
</IfModule>

<Location /protected>
    AuthType Basic
    AuthName "SSO Protected Area"
    AuthBasicProvider ldap
    AuthLDAPURL "ldap://ldap.example.com/dc=example,dc=com?uid"
    Require valid-user
    Session On
</Location>

For Windows installations, verify the modules are properly built and located in the modules directory. On Linux (SUSE/RHEL), ensure the package includes the required LDAP modules:

# For RHEL/CentOS
yum install mod_ldap mod_session

# For SUSE
zypper install apache2-mod_ldap apache2-mod_session

Enable verbose logging to troubleshoot LDAP issues:

LogLevel debug
LDAPLibraryDebug 7

Check loaded modules with:

httpd -M | grep -E 'ldap|session'

This error typically occurs when migrating from Apache 2.2.x to 2.4.x configurations, particularly during LDAP authentication setups. The AuthzLDAPAuthoritative directive was deprecated and removed in Apache 2.4, replaced by new authorization mechanisms.

The authorization system was completely redesigned in Apache 2.4, with these major changes:

# Old 2.2.x syntax (no longer works):
AuthzLDAPAuthoritative On
Require ldap-user karthik

# New 2.4.x syntax:
Require ldap-user karthik

Here's a working configuration for Apache 2.4 with LDAP and SSO via mod_session:

LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
LoadModule session_module modules/mod_session.so
LoadModule session_cookie_module modules/mod_session_cookie.so

<VirtualHost *:80>
    ServerName sso.example.com
    
    # LDAP Configuration
    AuthType Basic
    AuthName "LDAP Authentication"
    AuthBasicProvider ldap
    AuthLDAPURL "ldap://ldap.example.com:389/dc=example,dc=com?uid?sub"
    AuthLDAPBindDN "cn=admin,dc=example,dc=com"
    AuthLDAPBindPassword "secret"

    # Authorization - New 2.4 style
    <RequireAll>
        Require valid-user
        # Additional requirements can go here
    </RequireAll>

    # Session Configuration
    Session On
    SessionCookieName session path=/
    SessionCryptoPassphrase secretphrase
</VirtualHost>

• Remove all AuthzLDAPAuthoritative directives
• Replace Order/Allow/Deny with Require directives
• Ensure all required modules are loaded (authnz_ldap, session)
• Verify LDAP connection strings are valid

If issues persist after migration, check:

# Verify loaded modules
httpd -M | grep -E 'authnz_ldap|session'

# Check syntax
apachectl configtest

# Debug LDAP connections
LogLevel debug authnz_ldap:debug session:debug

For production environments using LDAP with SSO:

# Enable LDAP connection pooling
AuthLDAPInitialBindAsUser on
AuthLDAPMaxSubGroupDepth 5
AuthLDAPConnectionPoolTTL 300