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Note: Apache on Fedora and CentOS may be called httpd

== Errors ==

Use either of the below commands to check the apache2 configuration:

<pre>apache2 -t
apache2ctl -t
apache2ctl -configtest

#and the status
/etc/init.d/apache2 status
/etc/init.d/httpd status</pre>

=== Mime Types ===	 
	 
A common issue is being only able to either download or view a PDF. This needs to either be added in the /etc/mime.types with:	 
<pre>application/pdf .pdf</pre>	 
Or the .htaccess file for that domain or /etc/apache2/mods-enabled/mime.conf with:	 
<pre>AddType application/pdf .pdf</pre>

=== New web server configuration ===

''New files of configuration for Apache web server were not built due to errors in configuration templates. The detailed error message was e-mailed to you, so please check the e-mail, fix the errors, and click here to retry generating configuration '''or''' New web server configuration for some domains within the marked subscriptions was not built due to errors in configuration templates. The detailed error message was e-mailed to you, so please check the e-mail, fix the errors, and click here to retry generating configuration.'' 

''apache2: bad user name ${APACHE_RUN_USER} ("Apache2 bad user name $ apache run user")'' or

''apache2: Syntax error on line X of /etc/apache2/apache2.conf: Syntax error on line X of /etc/apache2/conf.d/zz010_psa_httpd.conf: Syntax error on line X of /opt/psa/admin/conf/vhosts_bootstrap.conf: Could not open configuration file''

'''Fixs:'''

If it is complaining about a user name, check if this was an FTP or Email account, or a User under Customers or Users. You can sometimes suspend the offending domain to temporarily resolve the issue.

If when clicking the domain you get this sort of error below, see [http://kb.parallels.com/en/6661 this] Parallels KB article.

<pre>Internal error: Unable to load object of type SysUser with id=1: SysUser: unable to select: no such row in the table
Message    Unable to load object of type SysUser with id=1: SysUser: unable to select: no such row in the table
File    common_func.php3
Type    PleskFatalException</pre>

If you have removed a domain or SSL and do:

<pre>/etc/init.d/apache2 restart</pre>

You may get an error in /etc/apache2/apache2.conf

<pre>vim /etc/apache2/apache2.conf</pre>

Check the line in the error. It may then reference:

<pre>/etc/apache2/conf.d/zz010_psa_httpd.conf</pre>

Which references:

<pre>/opt/psa/admin/conf/vhosts_bootstrap.conf</pre>

Which will want to include the following type of file:

<pre>/var/www/vhosts/domain.com/conf/XXXXXXXXXXX.XXXXXXXX_httpd.include
/opt/psa/var/certificates/cert*</pre>

/var/www/vhosts/domain.com/conf

Run:

<pre>/usr/local/psa/admin/bin/httpdmng --reconfigure-all</pre>

If this does not work, run:

<pre>/usr/local/psa/bin/domain --remove domain.com</pre>

And then you may need to remove the include entries for the missing domain in:

<pre>/opt/psa/admin/conf/vhosts_bootstrap.conf</pre>

You '''MAY''' be able to remove some of the httpd.include files from here so it might not include them in the Apache configuration, however this has not been tried.

If this does not work and you are getting the following error:

''New files of configuration for Apache web server were not built due to errors in configuration templates: Syntax error on line XXX of /opt/psa/admin/conf/generated/13589366030.21908000_server.include: SSLCertificateFile: file '/opt/psa/var/certificates/certl8w1mkz' does not exist or is empty''

''ERR (3): Apache config (13589358830.79743100) generation failed: Syntax error on line 131 of /opt/psa/admin/conf/generated/13589358830.79743100_server.include:
SSLCertificateFile: file '/opt/psa/var/certificates/certl8w1mkz' does not exist or is empty''

Check [http://forum.parallels.com/showthread.php?t=262024 this] and then if that does not work do this:

<pre>ls -lah /opt/psa/var/certificates/
vim cert-xxXx00</pre>

Copy the contents of that file and input it into the one it says is missing:

<pre>vim certl8w1mkz
:wq
/etc/init.d/apache2 restart</pre>

This can also be caused due to the MySQL bug seen [http://kb.parallels.com/113620 here] as well. Do not upgrade Plesk to 10.4.4 on Ubuntu 8.04.

Alternate fixes:<br>
http://innovationframes.com/phpbb/viewtopic.php?f=33&t=274<br>
http://kb.parallels.com/en/111605<br>
[http://itslennysfault.com/rebuild-plesk-apache-httpd-conf-configuration-file/ Rebuild Plesk Apache httpd.conf configuration file]

=== SSL server IP/port conflict ===

This will normally appear in either /var/log/apache2/error.log or /var/log/syslog. It can be caused by Plesk's webmail clients horde.webmail:443 or atmail.webmail:443 conflicting with an SSL assigned to a domain.com:443

This can cause Apache to get stuck in a loop on startup and sometimes use 100% CPU usage. Either get another IP address, remove and re-add the domain/SSL, do not use webmail or configure it to use a different port.

=== Unable to start/restart Apache ===

If the following error appears after issuing /etc/init.d/apache2 start command

<pre>* Starting web server apache2      (98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs</pre>

It is normally what they call "hogging a port". You can use the following commands below to kill it and start it again. The issue as caused by apache hogging the HTTP port.

<pre>/etc/init.d/apache2 stop
kill -15 process
*wait 5-15 seconds*
kill -9 apache2
killall apache2
/etc/init.d/apache2 start</pre>

If it can continually be stopped and shows this when starting:

<pre>* Starting web server apache2
98)Address already in use: make_sock: could not bind to address 0.0.0.0:443
no listening sockets available, shutting down
Unable to open logs</pre>

Ensure /etc/apache2/ports.conf only has this in it:

<pre>NameVirtualHost *:80
Listen 80
<IfModule mod_ssl.c>
    Listen 443
</IfModule>
<IfModule mod_gnutls.c>
    Listen 443
</IfModule>
</pre>

If you get:

<pre>Service /etc/init.d/apache2 failed to start
websrvmng: /opt/psa/admin/bin/apache_control_adapter execution failed:

(20014)Internal error: Error retrieving pid file /var/run/apache2.pid
Remove it before continuing if it is corrupted.</pre>
Do this:
<pre>cd /var/run
mv apache2.pid apache2.pid.old
/etc/init.d/apache2 stop
/etc/init.d/apache2 start</pre>

=== Vhost Configuration Syntax ===

The below error indicates there may be spacing, closing and spelling issues with the vhosts configuration file or you have broken the apache configuration as in the header above.

<pre>Syntax error on line 1177 of /etc/apache2/apache2.conf:
Syntax error on line 151 of /etc/apache2/conf.d/zz010_psa_httpd.conf:
Syntax error on line 86 of /var/www/vhosts/domain.com/conf/httpd.include: 
Syntax error on line 1 of /var/www/vhosts/domain.com/conf/vhost.conf: 
/var/www/vhosts/domain.com/conf/vhost.conf:8: Less Than Greater Than was not closed.
\n/var/www/vhosts/domain.com/conf/vhost.conf:1: Less Than Greater Than was not closed.   [fail]</pre>

<pre>vim /var/www/vhosts/domain.com/conf/vhost.conf
/opt/psa/admin/sbin/websrvmng -av
/etc/init.d/apache2 start
 * Starting web server apache2</pre>

Normal Apache Virtual Host configuration
<pre><VirtualHost X.X.X.X:80>
ServerName "domain.co.uk:80"
ServerAlias "ipv4.domain.co.uk"
ServerAlias "www.domain.co.uk"
UseCanonicalName Off</pre>

== Cannot upload to website ==

Check the following location:

<pre>tail -f /var/www/vhosts/yourdomain.com/statistics/logs/error.log</pre>

If you see: 

<pre>mod_fcgid: HTTP request length 131100 (so far) exceeds MaxRequestLen (131072)</pre>

go into:

<pre>vim /etc/apache2/mods-available/fcgid.conf
#add the below between the <IfModule> and </IfModule> tags.
FcgidMaxRequestLen 1073741824 (or cgid for CGI)</pre>

It should appear in white if correct. Restart Apache using /etc/init.d/apache2 restart.

== Creating Virtual Hosts from scratch ==

This is using an Ubuntu 12.04, Apache 2.2.22 server as an example.

<pre>cd /var/www
mkdir sites ; cd sites ; mkdir yourdomain.co.uk
cd /etc/apache2/sites-available
vim domain.co.uk</pre>

Insert the following:

<pre><VirtualHost *:80>
    ServerAdmin admin@domain.co.uk
    DocumentRoot "/var/www/sites/domain.co.uk"
    ServerName domain.co.uk
    ServerAlias www.domain.co.uk
    #for subdomains just put the ServerAlias the same as ServerName
    ErrorLog "/var/log/apache2/domain.co.uk-error_log"
    CustomLog "/var/log/apache2/domain.co.uk--access_log" common
</VirtualHost></pre>

Note, if you have RewriteEngine On inside your vhost (Virtual Host), restart Apache and it says this:

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

This means you need to do:

<pre>a2enmod rewrite
/etc/init.d/apache2 restart</pre>

<pre>a2ensite domain.co.uk
[ -f /etc/init.d/httpd ] && service httpd restart ; [ -f /etc/init.d/apache2 ] && service apache2 restart
apache2ctl -t</pre>

To disable a site, do a2dissite domain.co.uk

== Extension Modules ==

Before installing, use apt-get update<br>
Search using apt-cache search <module name><br>
After installing, use /etc/init.d/apache2 restart

=== C Compiler (gcc) ===

<pre>apt-get install build-essential
y</pre>

=== Crypt:SSLEay, Net:SSL and SSLEay ===

These are commonly needed alongside OpenSSL and ModPerl.

Ubuntu:
<pre>apt-get install libnet-ssleay-perl libcrypt-ssleay-perl</pre>
CentOS:
<pre>yum install perl-Crypt-SSLeay.x86_64 perl-Net-SSLeay.x86_64</pre>
In case you need it for an additional module:
<pre>yum install php-pecl-apc.x86_64</pre>

=== libmcrypt ===

<pre>apt-get update
apt-cache search mcrypt
apt-get install <package name></pre>

Examples of libraries are libmcrypt-dev, libmcrypt4, libtomcrypt-dev, libtomcrypt and libtomcrypt0

=== mcrypt ===

<pre>apt-get install php5-mcrypt</pre>

=== mod_headers and mod_expires ===

<pre>a2enmod expires
a2enmod headers
service apache2 restart</pre>

expires is needed to set expiration dates on files (for caching)

=== mysql-devel ===

Under Ubuntu 10 this has been renamed to libmysqlclient16-dev and libmysql++-dev (or 15)

=== pear ===

<pre>apt-get install php-pear</pre>

You may need php-pear.noarch on CentOS. Alternatively you may need the EPEL repository installing:

<pre>wget serverkb.co.uk/tools/epel.sh ; chmod +x epel.sh ; ./epel.sh ; yum search pear</pre>

=== [http://www.google.co.uk/search?hl=en&source=hp&biw=1360&bih=648&q=apache+on+windows&gbv=2&oq=apache+on+windows&aq=f&aqi=g10&aql=&gs_sm=e&gs_upl=408l2309l0l2391l17l14l0l5l5l0l233l1520l1.6.2l9l0/ Using Apache on Windows] ===

As long as the IP address is not within IIS and no domains are assigned to it it should be possible. You may want this for tomcat statistics for example. It is not advised however as it is native to Linux.

== httpd dead but subsys locked ==

Googling this message comes back with a lot of different information regarding it. It can happen if a database using MySQL comes under high load and overloads the web server. Restarting/starting Apache/httpd normally fixes this.

== Manually create Virtual Hosts ==

== [http://www.devside.net/articles/apache-performance-tuning/ Performance Tuning] ==

As mentioned on the front page http://pingdom.com and http://slowcop.com are good places to start. For example, I improved the load speeds of this Wiki by enabling compression on the server by doing the following in SSH:

<pre>a2enmod deflate
vim /etc/apache2/mods-enabled/deflate.conf</pre>
Add in the following underneath the </IfModule>
<pre><Location />
  # Insert filter
  SetOutputFilter DEFLATE

  # Netscape 4.x has some problems...
  BrowserMatch ^Mozilla/4 gzip-only-text/html

  # Netscape 4.06-4.08 have some more problems
  BrowserMatch ^Mozilla/4\.0[678] no-gzip

  # MSIE masquerades as Netscape, but it is fine
  # BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
  # NOTE: Due to a bug in mod_setenvif up to Apache 2.0.48
  # the above regex won't work. You can use the following
  # workaround to get the desired effect:
  BrowserMatch \bMSI[E] !no-gzip !gzip-only-text/html

  # Don't compress images
  SetEnvIfNoCase Request_URI \
  \.(?:gif|jpe?g|png)$ no-gzip dont-vary
</Location></pre>

Then restart the web server: /etc/init.d/apache2 restart

If you do not use mod_perl or mod_python on your websites, disabling these may decrease memory usage.

== Premature end of script headers ==

This can be an indication the server has run out of RAM. This could be due to the amount of traffic, specific actions on the server or a deliberate attack on the server. Check the server status logs to see if there are spikes where the load on the server increases.

Check for any suspicious network traffic destined for your server. You can install a reactive firewall that will log and block a large range of deliberate attacks against your server. It's unlikely to have any side effects but if you do notice any changes to functionality of your site the rules can be relaxed or disabled.

Install apf http://www.rfxn.com/projects/advanced-policy-firewall . If the firewall prevents anything from functioning just do /etc/init.d/apf stop

Scan your site for Malware (e.g. Maldet or NOD32).

It's possible the issue is simply the legitimate traffic to the site putting more load on the server than it can handle. If you are using Wordpress use caching plugins. We would strongly recommend totalcache or supercache as these can dramatically improve the performance of Wordpress sites. RSS Feeds are notorious for attracting traffic.

== CGI scripts in arbitrary directories ==

* [http://www.microhowto.info/howto/allow_cgi_scripts_within_the_document_root_of_an_apache_webserver.html Allow CGI scripts in root]
* [http://httpd.apache.org/docs/2.0/howto/cgi.html Dynamic content with CGI]

== UID of script is smaller than min_uid ==

You likely need to chown the files to the right user:group
Return to Apache.
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