Apache HTTP Server Version 2.4
In order to assist folks upgrading, we maintain a document
describing information critical to existing Apache HTTP Server users. These
are intended to be brief notes, and you should be able to find
more information in either the New Features document, or in
src/CHANGES file. Application and module developers
can find a summary of API changes in the API updates overview.
This document describes changes in server behavior that might require you to change your configuration or how you use the server in order to continue using 2.4 as you are currently using 2.2. To take advantage of new features in 2.4, see the New Features document.
This document describes only the changes from 2.2 to 2.4. If you are upgrading from version 2.0, you should also consult the 2.0 to 2.2 upgrading document.
The compilation process is very similar to the one used in
version 2.2. Your old
configure command line (as
build/config.nice in the installed server
directory) can be used in most cases. There are some changes in
the default settings. Some details of changes:
mod_lbmethod_bybusyness. You might need to build and load any of these that your configuration uses.
LoadModuledirectives are commented out in the configuration file.
There have been significant changes in authorization configuration, and other minor configuration changes, that could require changes to your 2.2 configuration files before using them for 2.4.
Any configuration file that uses authorization will likely need changes.
You should review the Authentication, Authorization and Access Control Howto, especially the section Beyond just authorization which explains the new mechanisms for controlling the order in which the authorization directives are applied.
Directives that control how authorization modules respond when they don't match
the authenticated user have been removed: This includes
AuthzLDAPAuthoritative, AuthzDBDAuthoritative, AuthzDBMAuthoritative,
and AuthzOwnerAuthoritative. These directives have been replaced by the
If you use
mod_authz_dbm, you must port your
configuration to use
Require dbm-group ... in place
Require group ....
In 2.4, such access control is done in the same way as other
authorization checks, using the new module
mod_authz_host. The old access control idioms
should be replaced by the new authentication mechanisms,
although for compatibility with old configurations, the new
mod_access_compat is provided.
Mixing old directives like
Deny with new ones like
Require is technically possible
mod_access_compat was created to support
configurations containing only old directives to facilitate the 2.4 upgrade.
Please check the examples below to get a better idea about issues that might arise.
Here are some examples of old and new ways to do the same access control.
In this example, there is no authentication and all requests are denied.
Order deny,allow Deny from all
Require all denied
In this example, there is no authentication and all requests are allowed.
Order allow,deny Allow from all
Require all granted
In the following example, there is no authentication and all hosts in the example.org domain are allowed access; all other hosts are denied access.
Order Deny,Allow Deny from all Allow from example.org
Require host example.org
In the following example, mixing old and new directives leads to unexpected results.
DocumentRoot "/var/www/html" <Directory "/"> AllowOverride None Order deny,allow Deny from all </Directory> <Location "/server-status"> SetHandler server-status Require local </Location> access.log - GET /server-status 403 127.0.0.1 error.log - AH01797: client denied by server configuration: /var/www/html/server-status
Why httpd denies access to servers-status even if the configuration seems to allow it?
mod_access_compat directives take precedence
mod_authz_host one in this configuration
This example conversely works as expected:
DocumentRoot "/var/www/html" <Directory "/"> AllowOverride None Require all denied </Directory> <Location "/server-status"> SetHandler server-status Order deny,allow Deny from all Allow From 127.0.0.1 </Location> access.log - GET /server-status 200 127.0.0.1
So even if mixing configuration is still possible, please try to avoid it when upgrading: either keep old directives and then migrate to the new ones on a later stage or just migrate everything in bulk.
In many configurations with authentication, where the value of the
Satisfy was the default of ALL, snippets
that simply disabled host-based access control are omitted:
# 2.2 config that disables host-based access control and uses only authentication Order Deny,Allow Allow from all AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure Require valid-user
# No replacement of disabling host-based access control needed AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure Require valid-user
In configurations where both authentication and access control were meaningfully combined, the access control directives should be migrated. This example allows requests meeting both criteria:
Order allow,deny Deny from all # Satisfy ALL is the default Satisfy ALL Allow from 127.0.0.1 AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure Require valid-user
AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure <RequireAll> Require valid-user Require ip 127.0.0.1 </RequireAll>
In configurations where both authentication and access control were meaningfully combined, the access control directives should be migrated. This example allows requests meeting either criteria:
Order allow,deny Deny from all Satisfy any Allow from 127.0.0.1 AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure Require valid-user
AuthType Basic AuthBasicProvider file AuthUserFile /example.com/conf/users.passwd AuthName secure # Implicitly <RequireAny> Require valid-user Require ip 127.0.0.1
Some other small adjustments may be necessary for particular configurations as discussed below.
MaxRequestsPerChildhas been renamed to
MaxConnectionsPerChild, describes more accurately what it does. The old name is still supported.
MaxClientshas been renamed to
MaxRequestWorkers, which describes more accurately what it does. For async MPMs, like
event, the maximum number of clients is not equivalent than the number of worker threads. The old name is still supported.
DefaultTypedirective no longer has any effect, other than to emit a warning if it's used with any value other than
none. You need to use other configuration settings to replace it in 2.4.
AllowOverridenow defaults to
EnableSendfilenow defaults to Off.
FileETagnow defaults to "MTime Size" (without INode).
mod_dav_fs: The format of the
DavLockDBfile has changed for systems with inodes. The old
DavLockDBfile must be deleted on upgrade.
KeepAliveonly accepts values of
Off. Previously, any value other than "Off" or "0" was treated as "On".
Mutexdirective. You will need to evaluate any use of these removed directives in your 2.2 configuration to determine if they can just be deleted or will need to be replaced using
CacheIgnoreURLSessionIdentifiersnow does an exact match against the query string instead of a partial match. If your configuration was using partial strings, e.g. using
/someapplication/image.gif;jsessionid=123456789, then you will need to change to the full string
mod_cache: The second parameter to
CacheEnableonly matches forward proxy content if it begins with the correct protocol. In 2.2 and earlier, a parameter of '/' matched all content.
LDAPTrustedClientCertis now consistently a per-directory setting only. If you use this directive, review your configuration to make sure it is present in all the necessary directory contexts.
FilterProvidersyntax has changed and now uses a boolean expression to determine if a filter is applied.
DebugLeveloption has been removed in favour of per-module
DebugLeveloption has been removed in favour of per-module
mod_proxy_scgi: The default setting for
PATH_INFOhas changed from httpd 2.2, and some web applications will no longer operate properly with the new
PATH_INFOsetting. The previous setting can be restored by configuring the
mod_ssl: CRL based revocation checking now needs to be explicitly configured through
mod_substitute: The maximum line length is now limited to 1MB.
mod_reqtimeout: If the module is loaded, it will now set some default timeouts.
DumpIOLogLevelis no longer supported. Data is always logged at
CustomLogwere invoked using
/bin/sh -cin 2.2 and earlier. In 2.4 and later, piped logging commands are executed directly. To restore the old behaviour, see the piped logging documentation.
mod_autoindex: will now extract titles and display descriptions for .xhtml files, which were previously ignored.
mod_ssl: The default format of the
*_DNvariables has changed. The old format can still be used with the new
SSLOptions. The SSLv2 protocol is no longer supported.
SSLProxyCheckPeerExpirenow default to On, causing proxy requests to HTTPS hosts with bad or outdated certificates to fail with a 502 status code (Bad gateway)
htpasswdnow uses MD5 hash by default on all platforms.
NameVirtualHostdirective no longer has any effect, other than to emit a warning. Any address/port combination appearing in multiple virtual hosts is implicitly treated as a name-based virtual host.
mod_deflatewill now skip compression if it knows that the size overhead added by the compression is larger than the data to be compressed.
#if expr=element or the directive
SSILegacyExprParseris enabled for the directory containing the error documents.
mod_authn_aliasin previous versions (i.e., the
AuthnProviderAliasdirective) has been moved into
mod_rewritemodule using the
LogLeveldirective. See also the mod_rewrite logging section.
All modules must be recompiled for 2.4 before being loaded.
Many third-party modules designed for version 2.2 will otherwise work unchanged with the Apache HTTP Server version 2.4. Some will require changes; see the API update overview.
Invalid command 'User', perhaps misspelled or defined by a module not included in the server configuration- load module
Invalid command 'Require', perhaps misspelled or defined by a module not included in the server configuration, or
Invalid command 'Order', perhaps misspelled or defined by a module not included in the server configuration- load module
mod_access_compat, or update configuration to 2.4 authorization directives.
Ignoring deprecated use of DefaultType in line NN of /path/to/httpd.conf- remove
DefaultTypeand replace with other configuration settings.
Invalid command 'AddOutputFilterByType', perhaps misspelled or defined by a module not included in the server configuration-
AddOutputFilterByTypehas moved from the core to mod_filter, which must be loaded.