I was lurking, mostly checking out the information on the Unofficial patch and trying to find the install that allowed it to be installed as a Mod. (Honestly, it was rather difficult to find because it wasn't in the OP for the patch, and on the last page someone said it was just a few posts up, but I went through 20 pages and didn't find it. Had to go to another thread to get it, and it was just luck then.) I managed to get this error. Ironically, the SQL error page has an HTML error, which amounts to missing the < in the <html> tag. This is the page that I managed to get. This is not the source for the page, but rather, this is the actual page that appeared. I removed my IP for safety reasons
With that to, the mailto: address is blank as you can see, meaning even if the page did appear properly, the admin couldn't be emailed to be notified about the SQL server issue.

Code:
html>
<head>
<title>Civilization Fanatics' Forums Database Error</title>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<style type="text/css">
<!--
body { background-color: white; color: black; }
#container { width: 400px; }
#message { width: 400px; color: black; background-color: #FFFFCC; }
#bodytitle { font: 13pt/15pt verdana, arial, sans-serif; height: 35px; vertical-align: top; }
.bodytext { font: 8pt/11pt verdana, arial, sans-serif; }
a:link { font: 8pt/11pt verdana, arial, sans-serif; color: red; }
a:visited { font: 8pt/11pt verdana, arial, sans-serif; color: #4e4e4e; }
-->
</style>
</head>
<body>
<table cellpadding="3" cellspacing="5" id="container">
<tr>
<td><img src="./image.php?type=dberror" alt="Database Error" width="48" height="48" /></td>
<td id="bodytitle" width="100%">Database error</td>
</tr>
<tr>
<td class="bodytext" colspan="2">The Civilization Fanatics' Forums database has encountered a problem.</td>
</tr>
<tr>
<td colspan="2"><hr /></td>
</tr>
<tr>
<td class="bodytext" colspan="2">
Please try the following:
<ul>
<li>Load the page again by clicking the <a href="#" onclick="window.location = window.location;">Refresh</a> button in your web browser.</li>
<li>Open the <a href="/">forums.civfanatics.com</a> home page, then try to open another page.</li>
<li>Click the <a href="javascript:history.back(1)">Back</a> button to try another link.</li>
</ul>
</td>
</tr>
<tr>
<td class="bodytext" colspan="2">The forums.civfanatics.com forum technical staff have been notified of the error, though you may <a href="mailto:">contact them</a> if the problem persists.</td>
</tr>
<tr>
<td class="bodytext" colspan="2"> <br />We apologise for any inconvenience.</td>
</tr>
</table>
<!--
Database error in vBulletin 3.6.4:
Invalid SQL:
UPDATE session
SET lastactivity = 1203772364, location = '/downloads.php?do=file&amp;id=7288&amp;act=down', inforum = 0, inthread = 0, incalendar = 0, badlocation = 0
WHERE sessionhash = '35b19cc069bf505c066e1f96e3592b50';
MySQL Error : MySQL server has gone away
Error Number : 2006
Date : Saturday, February 23rd 2008 @ 07:29:51 AM
Script : http://forums.civfanatics.com/downloads.php?do=file&id=7288&act=down
Referrer : http://forums.civfanatics.com/downloads.php?do=file&id=7288
IP Address : ***.***.***.***
Username : Unregistered
Classname : vB_Database
-->
</body>
</html>
With that to, the mailto: address is blank as you can see, meaning even if the page did appear properly, the admin couldn't be emailed to be notified about the SQL server issue.