iText 5.0.0 released on December 7, 2009, and I noticed it has some big changes need you to pay attention to,

• Changed the license from MPL/LGPL to AGPL
• iText.jar is now compiled with Java 5
• Changed the package names from com.lowagie to com.itextpdf

Please visit How to fix pclzip_err_bad_format issue when automatically update Piwik

through my Piwik statics, I noticed many keywords focus on “pclzip_err_bad_format”, then I noticed Piwik 0.5 releases.
When I tried automatically update Piwik, I got the same issue with Piwik 0.45.
And I decided upgrade Piwik manually this time.
using ssh to login my host
download Piwik 0.5
wget http://piwik.org/latest.zip
back up config.ini.php
cp piwik/config/config.ini.php .
use the Piwik 0.5 replace the old version
unzip latest.zip
browser my Piwik website and finish the upgrade.