Changes made in November 2005 to the version of the MediaWiki software running Wikipedia altered the way signatures work. If your signature is not working now (but was working previously), you will need to make some changes to your Preferences page.

MediaWiki makes the creation of simple, straightforward signatures relatively easy. For example, if User:Example wants a signature that displays as Example, he would simply have to enter "Example" in the Signature field in Preferences. The software automatically places "Example" in [[User:Example|here]], to form [[User:Example|Example]]. When saved in a page, this markup displays as "Example". Wiki markup and HTML markup do not function in the Signature field, unless the "Treat the above as wiki markup" option is checked in Preferences.

For example, placing the following in the default Signature field

[[User:Example|Example]] : [[User talk:Example|Talk]]

will result in a signature that looks like

[[User:Example|Example]] : [[User talk:Example|Talk]] (talk)

instead of

Example : Talk

This is because Wiki markup (and HTML markup) are now escaped as HTML entities when placed in the default Signature field, e.g. [ instead of [.

If you would like a signature that requires markup within the Signature field, please check the "Treat the above as wiki markup" option and enter the full signature string into the field.

For instance, to produce the signature

Example : Talk

place

[[User:Example|Example]] : [[User talk:Example|Talk]]

within the Signature field and check the "Treat the above as wiki markup" option.

If you have been using "raw signatures" all along but find that your signature is now not working, you may find the following message displayed in your preferences:

Invalid raw signature; check HTML tags.

This means you are using invalid markup on your signature. Some possible causes with their corresponding solutions:

Unclosed tags

If you are opening a tag without the corresponding closing tag (for instance: [[User:Example|<span style="color:white">Example]]),
you should close the tag (for instance: [[User:Example|<span style="color:white">Example</span>]]).
It's also a good idea to put the tags outside the link if possible (for instance: <span style="font-family: serif">[[User:Example|Example]]</span>).

Mismatched or incorrectly nested tags

If the tags are mismatched (for instance: <s><u>hi</s></u>), fix them (for instance: <s><u>hi</u></s>).

Unquoted attributes

It's also recommended to use quotes on all attributes.
For instance, use <span style="color:white"></span> instead of <span style=color:white></span>.

Unclosed entities

If you have an HTML entity which is lacking the final ;, you need to add it; if you have a bare &, it must be replaced by &amp; (a bare & is always a mistake in either HTML or wikicode).

Unescaped special characters

If you are using one of &, < or > and want it shown as text, it must be escaped as &amp;, &lt; or &gt; respectively.

• Do not use a table. A table causes the signature to display on more than one line. Use span instead.

Remember that all wikilinks show up as bold black text on the page they link to. So if you are testing your signature on your userpage/talk page and the user/talk part of it doesn't show up as a link, that may be why.

The markup for your signature is visible in the edit window; if it is too long, it makes editing the page harder. Try to keep the markup length below about one line of text. Also, the signature length is, since 13 June 2006, restricted to 255 bytes (T10458, r22960), later changed to 255 characters (T12338, r23389).