I  have the same Problem on all Joomla 3.6.2 Websites with SEF Urls's.

Martin.

Hi Martin,

I found the reason and a fix for it. Essentially, the error occurs because Chameleon needs to parse the URL earlier than Joomla usually parses it. At that early stage in the process, the "System - Language Filter" plugin has not yet run. That plugin needs to operate first so that the language portion of the URL is parsed correctly e.g. /de/page-here has to be processed by the language filter to remove the /de/ from the beginning, so that the URL parser just parses /page-here.

The solution:
1 - go into the Plugin manager
2 - use the Search Tools button and "- select type -" to select the System plugins
3 - click at the top of the 1st column to sort by priority
4 - drag the "System - Language Filter" plugin to the top of the list of system plugins
Problem solved!

It's possible that there may be other plugins that define parse rules for URLs. If you come across other types of pages that give 404 errors, take a note of what component these occur on, then look through the system plugins to see if there's another plugin that may be defining a parse rule. If found, move it to the top of the list.

Please let me know how you get on.

Thanks,
Stephen