Which version of Joomla?
Which web browser?
If this was after an update can you confirm that you cleared the browser cache

Joomla 3.6.0
Chrome 51.0.2704.103

Clear cache solved the issue

Closing as this would be expected behaviour that cache needs to be cleared on an update

Cache issue - no issue to resolve. The JS is added with JFactory::getDocument()->addScriptDeclaration to the head of the admin document so it can have a CSRF token appended to it at load time. A Cache clear after update should be a must - or Joomla should implment cache busting.. which it currently doesnt.

Joomla actually started clearing its cache with the post update script - https://github.com/joomla/joomla-cms/blob/staging/administrator/components/com_admin/script.php#L1813

Problem is that it's only clearing the frontend cache. There's a cache for the backend too but that doesn't get flushed on update (you'd have to set the client_id state to "1" and trigger the clean method in the model again).

Now if you're talking about browser level cache, well, good luck...

@mbabker would you be able to do that PR please. It will save a LOT of aggravation on each update. I would do it myself if I knew how.

I can do it, it's two lines of code

Thanks - it will make a big difference
(I guess we wont need the message about clearing the cache any more then)

brian and for browser cache i proposed #11289 for (among other things) allow to attach the version string when using JHtml script methods (used all over the core).

Also adds the ability to add the script version when using JHtml::script() method.

The change in that PR will not solve the browser cache issues yet, but IMHO it's a first step.

Do I clear cache, or only expired cache?

@spetricko i suggest to ask on forums as Comments on closed Issues didn't get much Notice.