Manual:FAQ

Where do I download MediaWiki?
The latest stable release of MediaWiki can be downloaded from download.wikimedia.org or sourceforge.net. Files are supplied in a .tar.gz archive. MediaWiki can also be obtained direct from our Subversion repository. See also Download

How do I install MediaWiki?
Installing MediaWiki takes between 10 and 30 minutes, and involves uploading/copying files, and running the installer script to configure the software.

Full instructions can be found in the INSTALL file supplied in the distribution archive.

How do I install MediaWiki using a package?
Many Linux distributions provide MediaWiki in a packaged format for that distribution. The MediaWiki development team refers you to your Linux distribution for assistance with installing, configuring or using them. The individual communities & companies who maintain such packages should provide installation instructions.

Can I install more than one wiki on a server using MediaWiki?
It is possible to install more than one wiki on a server provided that:

OR
 * You use a different database for each wiki
 * You use a different database prefix for each wiki (for Postgres, you can achieve a similar effect by using different schemas and users)

For information on these options, see $wgDBname and $wgDBprefix respectively.

For information on setting up a wiki family, see Manual:Wiki family.

For information on an alternative way of setting up more than one wiki using the same server, database and source, see Steve Rumberg's excellent expose and additional comments from users.

Does MediaWiki work with safe_mode enabled?
Yes, but only to a limited degree. See Safe mode.

Does MediaWiki require shell access?
Shell access (SSH access) is not required for installing MediaWiki, but it is highly recommended. Without shell access, it may even be difficult for you to get a backup of your wiki, or to upgrade to a new version. So maintenance tasks will nto be possible at all without shell access.

How do I add extra namespaces?
To add a namespace, modify your LocalSettings.php file, and add namespaces via $wgExtraNamespaces. You can add the following code to add a "Portal" namespace, and its corresponding discussion namespace:


 * $wgExtraNamespaces = array(100 => "Portal", 101 => "Portal_talk");

Be sure to add underscores instead of spaces, such as in Portal_talk. Otherwise, the namespace will not be declared properly!

How do I enable uploading?
File uploads are an often-used feature of MediaWiki, but are disabled by default in all current release versions. To enable them, first make the upload directory (default images) writable by the web server (chmod 777 or allow the Apache user to write to it, etc.) then set $wgEnableUploads to true in LocalSettings.php (i.e. "$wgEnableUploads = true;"). See Manual:Configuring file uploads for more information.

How do I enable embedded math formulas?
MediaWiki allows embedded math formulas via a helper program called texvc that uses LaTeX to render the formulas. See Manual:Math for setup instructions.

How do I purge a cached page?
To purge a cached page, such as when making changes to the navigation bar, add &action=purge to the end of the page's dynamic URL.

e.g. http://www.mediawiki.org/w/index.php?title=Main_Page&action=purge

Note that the URL must be using the active directory name (/w/ by default) rather than the static one (/wiki/ by default). Attempting to append the purge command to a static URL (e.g. http://www.mediawiki.org/wiki/Main_Page&action=purge) will instead take you to a page name containing the purge command at the end (in this case, "Main Page&action=purge").

See also: Manual:Purge, Manual:Parameters_to_index.php

How do I allow uploading of additional formats?
MediaWiki requires that allowed file upload formats are specified using the $wgFileExtensions configuration directive. Usually this directive is situated in LocalSettings.php in the root of your MediaWiki installation.

For example, to allow uploading of PDF files, add the following to LocalSettings.php:

The syntax is different to allow uploading of more than one type of file. To do so, use an array as in the example below which will allow uploading of png, gif, jpg, jpeg, pdf, and txt files.

See Manual:Configuring file uploads for more information.

"File is corrupt or has an invalid extension"
Some users have reported that after adding a file format to the allowed extensions list, an error is encountered. The text of the error is similar to the following:


 * The file is corrupt or has an incorrect extension. Please check the file and upload again.

Possible solutions:


 * Set the value of $wgMimeDetectorCommand, e.g. under Unix or Linux, this would be
 * $wgMimeDetectorCommand = "file --brief --mime";
 * Compile/install the fileinfo PHP extension
 * Fedora - yum install php-pecl-Fileinfo

See Manual:Mime type detection for more information.

Initial user was not created by installer
Sometimes, the installer fails to create the default user, or the user table is lost for some reason. There are a couple of options for solving this:

maintenance/createAndPromote.php

 * Make sure AdminSettings.php is set up (see AdminSettings.sample)
 * Execute maintenance/createAndPromote.php</tt> from the shell

This will create a new user and promote them to an administrator. For help, run the script with the parameter --help</tt>.

Alter the database
above should be replaced with the appropriate user ID which you can see on the user's preference page
 * Register a new account using the regular method (Special:Userlogin).
 * Check the user ID in Special:Preferences.
 * Execute the following SQL statement against the database:
 * For MediaWiki 1.5 and later:
 * For MediaWiki 1.4:
 * For MediaWiki 1.3 and older:

How do I reset a password?
You can use the maintenance/changePassword.php</tt> maintenance script to reset a user's password.

You have to run the script from the command line. In other words, log into the server where your wiki is installed, then open a command prompt. Go to the installation directory, then go to the maintenance subdirectory. Run the following command:

php changePassword.php --user=someuser --password=somepass

Where obviously "somepass" is changed to the password you want to set and "someuser" is changed to the user name as it is listed in the table "user".

You can also use the old way, by modifying the database directly. Assuming that $wgPasswordSalt is set to true (the default), you can use the following SQL query for MySQL:

Where obviously "somepass" is changed to the password you want to set and "someuser" is changed to the user name as it is listed in the table "user".

The user_id</tt> in the CONCAT string is a column name and is not meant to be replaced with 'someuser'

If you obtain a 'dbname.user table does not exist' error, please check the LocalSettings.php file, and double-check the value for the $wgDBprefix variable. If that variable is not empty, try repeating the command, replacing $wgDBPreix_user</tt> instead of user</tt> in the UPDATE</tt> clause of the SQL statement.

If using PostGreSQL, use this query instead:

DB Expert Answer
If the external wiki is Wikipedia, and you wish to use the prefix "wp" to link to it, run this SQL statement to modify the Interwiki table in your database: The $1 indicates the article name on the external wiki.

Typical-User Answer
In a graphical SQL program (i.e. PhpMyAdmin), go to the interwiki table. Choose the option to insert (a row). In the iw_prefix field, enter your desired interwiki prefix. In the iw_url field, enter the Base URL of the external wiki plus the text "$1" as mentioned in the DB Expert Answer above. iw_local and iw_trans have default values of zero (0). You may leave them as zero.

For more information, see Help:Interwiki linking

Easy Answer
Install the Special:Interwiki extension. You can then add and remove interwiki entries through the Special:Interwiki special page.

How do I make my base URLs shorter? (i.e. /wiki/Article_Name as opposed to /w/index.php?title=Article_Name)
See Manual:Short URL.

Is downloading and using all of MediaWiki.org free?
Yes, it is free in the sense of Free software. See Project:Copyrights for licensing issues regarding the written content of this site.

How do I administrate/manage my users?
See Help:User rights.

Upgrading
Generic instructions on the upgrade process can be found in the UPGRADE</tt> file supplied with the software. See also Manual:Upgrading.

How do I change the logo?
The logo that appears in the top left of each page is determined by the $wgLogo configuration setting in the LocalSettings.php file.

To change this you simply need to change the value of $wgLogo to point to the URL of your own logo image. You can upload a file via the wiki and use that address (which allows it to be replaced easily, so you may want to protect the page if you use this method) or use an image uploaded to your server via other means.

It is possible to simply overwrite the default logo installed with MediaWiki, but this is strongly advised against, as an upgrade may end up overwriting it or change the default location of this file.

Tip: The logo image should be 135 pixels square.

How do I customize the logo in the top left corner? Can I?
The logo is a portlet block without a pBody section. It is identified by the p-logo id. The background image is specified by the wgLogo variable, which is defined in /includes/DefaultSettings.php. This location is relative to the web server root and not the system root. Redefine this in /LocalSettings.php to change the image. If set wrong there will be no image on the page; check your web server error log and adjust accordingly. However the size of the p-logo will need to be big enough for the logo if it is not to be clipped. This is set in the stylesheet (Main.css in monobook), under the p-logo style, the default setting is:

How do I customize the URL of the logo in the top left corner when you click it?
By default, clicking the logo takes you to the main page. If you want to change which page is the main page, edit MediaWiki:Mainpage. Or to make the link go to any arbitrary URL, for Monobook skin, edit Monobook.php and find and replace  with the URL of your choice and replace   with the desired link title.

Reducing the size of the logo
Note that a tag is on top of the logo so if you are trying to reduce the size of the logo's portlet you will also need to change the #p-logo a and #p-logo a:hover rules. The default setting for these is:

This simple customization will re-define the size of all of them at once... There is one more rule controlling the amount of space between the logo and first portlet in the side column - the padding on the top of #column-one. By default this is: If you want to remove the logo completely, comment out the wgLogo variable. Then set the column-one padding to a small value, such as 21:

You don't have to go edit the css file directly. You can go to <Your Wiki URL>?title=MediaWiki:Monobook.css. Hit edit and make your changes there. This has preference over the monobook main css.

How do I change the icon in the browser's address line (favicon)?

 * Simply replace the favicon.ico image file at the root of your wiki with the .ico image file you want.
 * Alternatively edit the $wgFavicon setting in LocalSettings.php and add $wgFavicon = "$wgScriptPath/path/to/your/favicon.ico";

Rewrite Rule
If you are using a rewrite rule in .htaccess to remove "index.php" from the URL, you will also need to add an exception for .ico files. Simply add the following rule to your .htaccess:


 * RewriteRule .*\.ico$ - [L]

This rule must appear before the index.php rule.

Case Sensitivity
When uploading the favicon file, be sure the filename is in lowercase. (That is, "favicon.ico", not "Favicon.ico".) A lot of servers (e.g., those on UNIX-like operating systems) will not be able to find the file unless its name is in lowercase.

How do I customize the navigation bar?
The contents of the navigation bar which appears to the left of each page using the Monobook skin are determined by the MediaWiki:Sidebar page. For information on customising these, please see Manual:Navigation bar.

How do I put a text message (sitenotice) on every page?
Put a text in the MediaWiki:Sitenotice page. It will be displayed on top of every article page.

How do I change the main page?
By default, MediaWiki looks for a page with the title Main Page and serves this as the default page. This can be changed by altering the contents of MediaWiki:Mainpage to point to a different title. If this does not change the 'Main Page' link included on the sidebar at install time, edit MediaWiki:Sidebar.

How do I hide the main page title?
MediaWiki does not have a built-in option to hide the main page title (see bug 6129). Instead you must use JavaScript or CSS.

Pre-1.9
Before MediaWiki 1.9, you will need to use JavaScript. Some code that may or may not work is as follows (replace "Main Page" with the name of your main page if it differs):

Alternatively, you can manually apply the patch from r17119 to your copy of MediaWiki and use the solution for 1.9.

1.9 and above
In 1.9 and above, you can rely on CSS to hide it. Replace "Main_Page" with the appropriate page name, here with spaces replaced by underscores.

If that doesn't work, look at the HTML source code to find the correct class to replace "page-Main_Page" with:

If no such class exists, then you cannot use this feature. You may be using a custom or outdated skin.

How can I hide the table of contents?
The table of contents (TOC) is automatically shown once there are four or more headings in the article. The are multiple ways to hide it.

For one page
Place the magic word  </tt> into the page markup.

For all pages
Edit the CSS files; locate the style for the table of contents and add display: none;</tt> to the definition.

Per user
Users can also opt to have the table of contents hidden. This is a user preference, set in Special:Preferences.

How do I change the interface text?
Interface text is altered using the MediaWiki namespace. For each deviation from the default in the site language there is a page MediaWiki:Englishmessagename, and for each deviation from the default in each other language a page MediaWiki:Englishmessagename/languagecode. (Since release 1.9 there are no pages for messages equal to the default.). On creation of a page the edit box autofills with the default. When creating a page to override the default it is useful to first save the default version, to allow diffs with it. See also meta:Help:System messages.


 * For a list of system messages, see Special:Allmessages
 * To switch off the MediaWiki namespace, see the $wgUseDatabaseMessages configuration setting
 * To remove the Privacy policy or Disclaimers links at the bottom of each page, set the content of pages MediaWiki:Privacy or MediaWiki:Disclaimers respectively to a single minus sign.

How do I change the interface language?
To change the default interface language, alter the value of $wgLanguageCode</tt> in LocalSettings.php</tt>, e.g.



How can I prevent editing by anonymous users?

 * 1) The recommended method is by changing the value of the  configuration option. Edit   and add the line: For more information on using these options, see the Preventing access page.
 * 2) Alternatively you could manually edit each skin's PHP source to not display the relevant tabs.


 * For the default MonoBook skin, search for this line in the  file:
 * and insert this conditional around the code inside the  block:
 * and insert this conditional around the code inside the  block:


 * Don't forget the closing brace on the new conditional.


 * To conditionally hide individual tabs, modify the code to check the value of each $key inside the foreach loop. Or you can write a 'hook' extension (around SkinTemplateXYZ) to modify the tab list.

How do I remove the article/edit etc tabs for users who are not logged in?
See How can I prevent editing by anonymous users?

How do I add/remove tabs in general?
To (for example) remove the talk tab and then add one that always goes to the main page you would save this code in (for example) extensions/AR-Tabs.php: and then add to the bottom of LocalSettings.php

How do I hide the section edit links for users who are not logged in?

 * 1) The recommended method is by changing the value of the  configuration option. Edit   and add the line:
 * 2) Alternatively you could manually edit each skin (e.g. ) and add this before  :


 * If you want to hide the links for all users including logged in users, instead edit  and add:


 * Also see How can I prevent editing by anonymous users?

How do I remove the "Talk for this IP" link at the top right when $wgDisableAnonTalk is true
In SkinTemplate.php line 489 (in version 1.9.2 - 1.11) change

to

and lines 547 - 554 from to (adding the if statement and indenting existing lines)

How do I remove the "Create an Account or Login" link at the top right of the screen?
In Monobook.php change this statement: to:

How do I change the footer?
To add or remove items from the footer on your MediaWiki page, you must edit the skin.

For example: if you go in to MonoBook.php (located by default in the "Skins" folder) you will find the following code:

In the above you can simply add and remove items from the footer that you wish to appear in your footer. Remember the changes may not appear immediatly because of MediaWiki caches.

You can also customize the individual items by modifying certain pages or parameters:
 * lastmod - edit MediaWiki:Lastmodifiedat (verison 1.8 and after) or MediaWiki:Lastmodified (version 1.7 and before). If $wgMaxCredits is enabled, then edit MediaWiki:Lastmodifiedatby (verison 1.8 and after) or MediaWiki:lastmodifiedby (version 1.7 and before). (6518)
 * viewcount - edit MediaWiki:Viewcount
 * numberofwatchingusers - edit MediaWiki:Number of watching users pageview. This only appears if you also add  to LocalSettings.php.
 * copyright - edit MediaWiki:Copyright. The parameter $1 on that page is replaced with a link to the details of copyright for your wiki. In LocalSettings.php $wgRightsText for the link text and set either $wgRightsPage or $wgRightsUrl with the location of a wiki page or external URL.
 * privacy - this is a link only. Edit MediaWiki:Privacy for the link text and MediaWiki:Privacypage for the wiki page to which to link.
 * about - this is a link only. Edit MediaWiki:Aboutsite for the link text and MediaWiki:Aboutpage for the wiki page to which to link.
 * disclaimer - this is a link only. Edit MediaWiki:Disclaimers for the link text and MediaWiki:Disclaimerpage for the wiki page to which to link.
 * tagline - not currently used in the footer

See also: Footer, Manual:Skinning

For line breaks in the footer, search for Content is available under in the MessagesEn.php and then put line breaks before and after so that it looks like  It is valid XHTML 1.0 Transitional.
 * Line breaks in footer

How can I edit / remove the Powered by MediaWiki image in the footer?
You can hide the Powered by MediaWiki image by adding the following to your wiki's MediaWiki:Common.css:

If you want to remove it completely, you could alter /skins/MonoBook.php</tt>, which contains the following code that makes the Powered by MediaWiki image appear in the footer: If you would like to remove this image completely, or edit the image, you must locate and edit poweredbyico. It is located in skins/common/images/</tt> and the image is called poweredby_mediawiki_88x31.png</tt>.

How can I change what the of each page is? Where do I make changes?
Most of the text that you want to change, can be found in the namespace of MediaWiki.

In order to change titles, texts, announcements and the such, go to Special:Allmessages, where you will see the text associated with the pages you wish to change. (As far as I can tell, you need to log in as an administrator (like the one you made when you installed) to edit the protected entries in the MediaWiki namespace.)

If you want to change the title in your browser, you need to edit MediaWiki:pagetitle. Go there and edit it just like you would any other page in your Wiki.

In recent versions of MediaWiki, MediaWiki:Pagetitle is $1 - by default. If is producing the wrong text for you, you need to set $wgSitename in your LocalSettings.php.

If $wgSitename is correct in LocalSettings.php but is still wrong, it may be that you're using a user-contributed language file which incorrectly sets $wgSitename to a transliteration of "Wikipedia". Edit the language file to correct this. For example, the hebrew language file is at languages/LanguageHe.php</tt> in your wiki directory.

Don't forget to clear your browser cache after you fix it.

How do I make external links open in a new window?
See Opening external links in a new window.

How can I suppress MediaWiki to format urls, tags, etc?
svn co http://somwhere.in.the.net/myproject/ svn co http://somewhere.in.the.net/myproject/

How can I force users to preview before they save?
To curb cursory negligence it may be desirable to disable the save button on the edit page, so users must preview first.

Here's how to reach that goal by only showing the save button on the preview page:

In /includes/EditPage.php, find (line number 1238 in MediaWiki 1.9.0, 1158 in MediaWiki 1.8.2): and replace these three lines with the following seven


 * See also: Manual:Force preview.

How do I add more buttons on the edit page?
For adding more toolbar buttons above the edit field, you can use JavaScript code to register them in <tt>mwCustomEditButtons</tt> in your MediaWiki:common.js. For example, a button for large text:

How can I get more special characters or tags clickable on the edit page?
For adding more selectable special characters, etc, below the edit field, See Extension:CharInsert

How do I edit a page?
To edit a page, simply click the edit link that appears on each page. Using the default MonoBook skin, this is in the form of a tab at the top of the page. A form will appear, containing the existing markup. When you have finished making modifications, click the Save button to commit your changes.

See also:

How do I create a new page?
There are several paths to creating a new page:

On some wikis, a failed search for a page will contain a link which allows you to edit that page.
 * Create a link to the page on another page, then click on the red link which appears
 * Browse to the intended location of the page, e.g. http://www.foowiki.org/index.php?title=New_page and click on the edit link.

See Help:Starting a new page

How do I delete an old version of a page?
Old versions of page data are retained in the database and can be accessed via the page history features. This is useful for reviewing changes and correcting or reverting undesirable ones, but in some cases, administrators might want to make this information unavailable, for legal reasons, or to reduce the size of the database.


 * Administrators can delete an old revision of a page by deleting the page, and then selectively undeleting revisions to be kept
 * The Oversight extension (also known as HideRevision) can be used to move harmful revisions out of page histories
 * The <tt>maintenance/deleteOldRevisions.php</tt> maintenance script can mass-delete all old revisions of pages and their associated text records. In order to run this maintenance script, have a look to this page.

Are there any editing tutorials available?
There are several editing tutorials available, mostly on Wikimedia sister projects, such as Wikipedia. There are also markup references, etc. available on Meta.


 * Editing help content on Meta
 * The How to edit a page guide on the English Wikipedia

How do I view the printable form of a page?
MediaWiki includes stylesheets which automatically style a page appropriately when it is printed; using the print or print preview function within your browser ought to render the page in a printable form.

You can also view this printable form using the printable version link in the toolbox.

How can I allow use of HTML tags?
See Manual:$wgRawHtml as well as Manual:$wgGroupPermissions and Manual:Preventing access.

This can be easily abused to attack users

See Extension:SecureHTML and Extension:HTMLets for ways to make this safe(er).

How can I allow uploading of HTML files?
See Manual:Allowing HTML Uploads.

This can be easily abused to attack users

...is the Help namespace empty?
We don't currently have a clean, internationalised set of help pages under a free license. A few developers are hoping to make this possible; however, the Help namespace currently ships in a blank state. You are free to add your own help pages, copy the Public Domain help pages or copy certain of the items from Meta, e.g. the user guide or MediaWiki Handbook, these two collections being free to use under the GNU Free Documentation License.

...are some of my images not showing up after an upgrade?
Several users have reported that, following an upgrade or a moving of their wiki, several images fail to be shown inline. The files exist, and the image description pages show a MIME type of <tt>unknown / unknown</tt> and, in some cases, a warning about potentially dangerous files.

To fix this, run the <tt>maintenance/rebuildImages.php</tt> script from the command line. This will set MIME information for each file in the database.

...are all PNG files not being turned into thumbnails?
After upgrading to a more recent version of PHP, it is possible a different MimeMagic.php function is being used to detect file MIME types, particularly the built-in PHP function mime_content_type, which fails to detect PNG files. Search the web for mime_content_type png for information on fixing this bug at the PHP level, possibly by editing your magic.mime file.

See here for more info.

...is a search for a short keyword giving no hits?
By default, MediaWiki uses MyISAM's fulltext matching functionality to allow searching page content. The default settings for this mean that words of less than four characters won't be indexed, so results won't be returned for those queries.

To alter this behaviour, MySQL needs to be reconfigured to index shorter terms, and MediaWiki's search index table needs to be repaired, to rebuild the indices.


 * For help on reconfiguring MySQL, see http://dev.mysql.com/doc/refman/4.1/en/fulltext-fine-tuning.html
 * To repair the search index table, run the query  against your database

...can't I download MediaWiki 1.12?
MediaWiki 1.12 is in a development state at present, and has not been packaged into a general release. The code can be downloaded from Subversion if desired.

...doesn't this work? It works on Wikipedia!
Wikipedia and other Wikimedia web sites use the current version of the code in development; at present, this is MediaWiki 1.12alpha. Coupled with the use of several extensions, this means that functionality between these wikis and your particular setup may differ.


 * To obtain the current development code, read Important Release Notes
 * To check what version a Wikimedia wiki is running, as well as what extensions are installed, visit the Special:Version page for that wiki

...do I get a 403 Forbidden error after setting permissions on my Fedora system?
Fedora Core enables SELinux by default. Instructions for setting SELinux permissions for MediaWiki are available.

...do I get logged out constantly?
This is probably related to cookies or session data, for example a problem with PHP's session.save_path setting. See Log in problems.

...is it a good idea to keep user accounts?
At many times you just want to remove a user account out of the wiki either because it belonged to a spammer account or you just feel like it. The appropriate choice is to block the account or rename it if needed. Here is why:

Do I just remove his row from the User table?

Rob Church posted the following regarding this issue on the mediawiki-l mailing list:

"If the user has made edits, then removing rows from the user table cause theoretical loss of referential integrity. Now, to be honest with you, I can't think of any conditions where this would cause an actual problem; "undefined behaviour" is the phrase we use.

What I'd suggest doing, to be on the safe side, is running a couple of quick updates against the database:



What this will do is cause MediaWiki to treat the revisions as having been made anonymously when generating things like page histories, which should eliminate any problems caused by these routines attempting to check user details from other tables.

If the user has caused log entries, i.e. rows in the logging table, or uploaded images, then the situation becomes trickier, as you'll have to start mopping up all the rows everywhere and it could become a bit of a mess, so if the user's done anything other than edit, I would strongly recommend just blocking them indefinitely.

If the username is offensive or undesirable, then you could consider renaming it using the RenameUser extension."

Anti-spam
See Manual:Combating spam for an overview of anti-spam measures.

Where do I get the spam blacklist from and how do I install it?
The spam blacklist extension can be found in Subversion. For installation and configuration instructions, consult the README file.

How do I use $wgSpamRegex to block more than one string?
$wgSpamRegex is a powerful filter for page content. Adding multiple items to the regex, however, can be awkward. Consider this snippet:

This example code allows convenient addition of additional items to the regex without fiddling about each time. It also demonstrates two popular filters, which block some of the most common spam attacks.

I've found a bug or have a feature request. Where do I post it?
Bugs and feature requests should be posted on MediaZilla, our implementation of Bugzilla. Please search the database prior to posting, to avoid creating duplicate entries.

I have a question not answered here. Where do I go next?
If you've exhausted the FAQ above, please try the following:


 * Check the other sources of help on this site
 * Search the rest of this site
 * Search our documentation archived on Meta
 * Useful developer documentation remains on Meta.wikimedia.org in the category Pages to be exported to MediaWiki.org until the m:Meta:MetaProject to transfer content to MediaWiki.org completes
 * How to become a MediaWiki hacker
 * How to debug MediaWiki
 * Search the web
 * Post a message at Project:Support desk
 * Email the mediawiki-l mailing list
 * Ask the developers in our IRC channel (Freenode network, channel #mediawiki).

Recommended reading

 * Asking smart questions
 * Effective bug reporting
 * MediaWiki Book: MediaWiki Administrators' Tutorial Guide.