I have just upgraded to 0.7 from 0.6.4 this afternoon, the primary reason being the introduction of the PDFReports plugin and the ability to email out reports on a scheduled basis.
Post upgrade, our Superuser went to the Plugins Admin page to enable the PDFReports plugin.
Upon attempting to activate, he is returned back to Plugins Admin, and it is still showing the activate link for this plugin.
The expected result, being PDF appearing in the top menu is not occurring. He advises that no error message or fault notification is being displayed.
This leads me to believe that the plugin has not activated, and according to the Superuser there is no logs at least he is aware of which could be used to diagnose why the plugin won't activate.
Keywords: pdfreports, pdf
Solved. Issue arose due to lack of write permissions on config/config.ini.php.
Would be worth moving this ticket as a suggestion, to improve error message generation in the event an action (such as activating a plugin) fails.
I just set config.ini.php to read-only, and Piwik prominently displays at the top:
The Piwik configuration file (config/config.ini.php) is not writable, some of your changes might not be saved. Please change permissions of the config file to make it writable.