Control Panel Breaks When Upgrading to 2.5.0
From Joomla! Documentation
The "J2.5" namespace is a namespace scheduled to be archived. This page contains information for a Joomla! version which is no longer supported. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.
When upgrading from 1.7.3 to 2.5.0, the Control Panel may appear "broken" after the upgrade. See the image on this page.
Cause[edit]
This issue is caused by changes to the Administrative template.
How to Fix[edit]
The fix is to clear your browser's cache.
- Mozilla / Firefox / Safari: hold Shift while clicking Reload, or press either Ctrl-F5 or Ctrl-R (Command-R on a Macintosh); Konqueror: click Reload or press F5; Opera: clear the cache in Tools → Preferences; Internet Explorer: hold Ctrl while clicking Refresh, or press Ctrl-F5.