Piwik 0.5.2 out, but when you try to automatically update it, you still meet pclzip_err_bad_format error. I do not want to manually update it every time, so I decide to find out the issue, from the keyword, “pclzip_err_bad_format”, I think maybe something wrong with PclZip.
The version of PclZip in Piwik is 2.8, but the last version of PclZip is 2.8.2, so I download the last version PclZip, unzip and replace the old version in Piwik, then the issue is gone.
the step in details is,
download the last version PclZip , or you can download it from here directly,

• wget http://stat.steedsoft.com/pclzip-2-8-2.tgz
• tar -zxfv pclzip-2-8-2.tgz
• cp piwik/libs/PclZip/pclzip.lib.php piwik/libs/PclZip/pclzip.lib.php.org
• cp pclzip.lib.php piwik/libs/PclZip/pclzip.lib.php
• do the automatically update now.

P.S.
I think I had better suggest Piwik team to update PclZip, so every can easily update Piwik from next version.

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.

Please visit How to fix pclzip_err_bad_format issue when automatically update Piwik

Piwik releases the new version 0.4.5, but when I tried to use Automatically update, I got the following error message,

Incompatible archive: PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature

After search, I got the answer, it is a bug of version 0.4.5, and has been fixed in svn, seems I’d better await the Piwik 0.5