after upgrading to 1.4 my working Piwik Installation works no more. The Widgets show “No data …” , live visitors were not shown, the visitor graph went to zero.
What to do? How to repair this?
(Installation went fine so far, Piwik shows itself as 1.4.)
I checked all the aspects in the document you linked – everything seemed to be okay. (I expected this for Piwik worked fine so far before the upgrade.)
Then I made a manual upgrade instead of the automatic one I did before – now everything works fine again. Something must have gone wrong during the automatic upgrade process.