We are officially advising all our users and customers to NOT upgrade to Joomla 1.5.16/1.5.17. The new Joomla release includes a auto-plugin disable feature which can lead to a site experiencing unexpected behavior or worst case the site could go down.

The auto-plugin disable feature was introduced to quote :<:p>

I'd like to try to write a patch to Joomla core so it doesn't die with fatal error when it can't include a plugin file (in other words: plugin exists in DB but filesystem entry is deleted).

Source : http://groups.google.com/group/joomla-dev-cms/browse_thread/thread/afee26baacf92c9f/c8b7d8e4952be51a?show_docid=c8b7d8e4952be51a

The introduced solution for this problem is that Joomla 1.5.16 and 1.5.17 now disables any plugin that triggers an error during initialisation.

The behavior assumes that a plugin would always throw an error, being a missing file, however the error could be conditional and only thrown under certain circumstances. Depending on how the plugin works the conditions could be rare. Instead of throwing an error the plugin is disabled and prevented from executing under normal conditions. This can lead to a site visitor experiencing unexpected behavior or worse the site could go down.

We have requested the change in 1.5.17 to be rolled-back. See : http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=19859. In the mean time we strongly advise you to not upgrade to Joomla 1.5.16/1.5.17.

If you are using 1.5.16/1.5.17 and you are experiencing problem with plugins magically disabling themselves please let us know.

Read original post at source site... http://feeds.joomlatools.org/~r/site/blog/~3/mRSM3o7k8uw/advising-to-not-upgrade-to-joomla.html