Interesting – an older version allowed the update despite an old PHP version which broke the install. Now that I downgraded to 2.17.1 it’s not allowing the update.
@stml Luckily downgrading is really easy.
- Downloaded the file: http://builds.piwik.org/piwik-2.17.1.tar.gz
- Moved old Piwik to a backup location and unpacked the fresh Piwik to replace the old one
- Copied over the old config: cp oldpiwik/config/config.ini.php piwik/config/config.ini.php
- Copied over geolocation file: cp oldpiwik/misc/GeoIPCity.dat piwik/misc/
Piwik should create the tmp/cache directory by itself on first load, and you are done.