I have a problem for upgrade my piwik (0.5) to 0.5.1 the message is :
Archive incompatible: PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature Piwik One Click Update has been cancelled. If you can't fix the above error message, it is recommended that you manually update Piwik. Please check out the Update documentation to get started! [\code] any idea ?