Support

Try the following:
- Clear your browser's cache and its cookies cache
- Quit your browser
- Reopen your browser
- Empty the contents of your site's jos_session table (where jos_ must be replaced with your site's database table name prefix, which might be different than jos_. It's easy to spot it, just look at the common prefix in all tables' names). EXTREMELY IMPORTANT! DO NOT DROP (DELETE) THE TABLE! We need you to empty its contents, an operation which is usually called "Truncate" in most database administration tools.
- Retry logging in

Well, the problem is not with Admin Tools. Renaming the plugin's file causes the plugin to no longer execute, therefore there is no Admin Tools' code executing in the back-end (or the front-end) of your site. This sounds like a problem with your site or a third party plugin. Following the method outlined above you can re-login to your site, set the session expiration time in Global Configuration to something really big (2000 minutes are plenty!) and then try disabling system plugins to see which one may cause this issue.

If you don't believe me when I say that Admin Tools has nothing to do with this, you can try the manual uninstallation method outlined midway through our release announcement.

I'll put it as simply as I can.

When you enable the "System - Admin Tools" plugin in your site, you tell Joomla! that on each and every page load it will have to look for a file named plugins/system/admintools.php or plugins/system/admintools/admintools.php and load it. When you rename that file to .php.bak the file is not loaded, because Joomla! does not load the php.bak file. Hence the documentation suggestion of renaming files.

A component, on the other hand, will only load when you try accessing the component. Since we are talking about a back-end component, it would only load if and only if the URL contains option=com_admintools. In any other case it does not load. In fact, when Joomla! sees option=com_foobar in the back-end URL, it will try to load the file administrator/components/com_foobar/foobar.php. If this file does not exist, nothing gets loaded from that component.

As you might imagine, code is something which can not run if it's not loaded. It's the reason you can not, let's say, run Admin Tools if you do not install it on your site. Therefore if what you described that you did on your site was within any degree of accuracy, here's what happened:
- After upgrading Joomla! (with Admin Tools loading), you got an error
- You renamed Admin Tools plugin's entry point file to php.bak, therefore Admin Tools was not loading at all. The problem remained.
- You renamed the php.bak file back to .php, therefore Admin Tools' plugin WAS LOADING and the problem DISAPPEARED.
- You removed Admin Tools, therefore its code was not loading and the problem didn't occur.

Therefore the problem occurred twice while both using AND not using Admin Tools and stopped occurring twice while both using AND not using Admin Tools. As a result, the problem IS NOT related to Admin Tools.

Put otherwise. At this point in time there are about 10,000+ Joomla! 1.5.x sites running Admin Tools. You are the only one reporting such an issue. Don't you think that if Admin Tools caused inability to login to Joomla! 1.5.26 sites I would be buried in support requests and would have received major outcry? Statistically speaking, it's extremely unlikely that there is such a grave issue with Admin Tools which only chose to manifest on your particular site.

So, can you please tell me how you came to the conclusion that Admin Tools has anything to do with your issue, especially since while Admin Tools was not activated your problem persisted? I know exactly what the problem is (stale Joomla! sessions), I know they are not related to Admin Tools (in fact, Admin Tools has an optional feature in the plugin to fix this issue with Joomla!...) but I can't convince you. You are free to believe whatever you want. That's as far as I can go with helping you.

Well, I try to have an answer for everything because I am asked pretty much about everything in this ticket system. Given the depth and breadth of the administrative extensions I write, I can safely expect to be asked about the most crazy and technical subjects - which is pretty much why I can't find anyone to help me with support :)

I will tell you exactly which point tipped me off as to why Admin Tools wasn't the culprit in this case. When you renamed the plugin file (therefore no Admin Tools code was running on your site) the problem persisted. This troubleshooting step broke the link between Admin Tools and the issue for me, so I started thinking what could the problem be.

The next step to understanding the issue is based on my experience with broken sessions. A few versions ago, Joomla! was complaining about Invalid Token. Same thing. Purging the cookies and the session table eventually resets Joomla!'s sessions and everything starts working. That's why I insisted in doing these steps in the order given. If you try to log into or visit your site after restarting the browser and before purging the sessions table you're back to square one.

The final step into understanding why this issue happened requires knowing what was changed between 1.5.25 and 1.5.26. The cryptic security announcement hints us that what was changes has something to do with inadequate randomness etc. Ultimately, this has to do with how Joomla! 1.5.25 and earlier handled user sessions and how that was changed in 1.5.26.

Combining all of the above (troubleshooting steps, experience, knowledge of what was changed) allows me to know within a very good degree of certainty what is going wrong. Normally, Joomla! should trash old sessions and ask you to log in again to your site. Well, sometimes sessions get stuck, hence the need to purge the sessions table and cookies.