Piwik is really great software, but from 0.45, the automatically update does work any more, it is really a big issue.
and today I found it is the bug of PclZip, so please update the PclZip library to the last version, and for the user who has install the Piwik, please following the article to update PclZip,
How to fix pclzip_err_bad_format issue when automatically update Piwik
btw, had better Piwik team update PclZip first, or after we update our Piwik, the PclZip library will be replaced with older version again.
this forum does insert link, so I have to remove http, but you can copy and past the link to the browser to find the tutorial.