I have 2 separate installations of Magento in different sub-domains on the same host.
The first one, my development store where I test upgrades, try out new add-ons etc. upgraded from 1.8.1 to 1.9.1 just fine (I used the upgrade in Magento Connect) apart from a couple of minor colour issues in a 3rd party template which were easily fixed.
I have just tried to upgrade the live store using exactly the same method and it crashed out part way through (got a cache flushing error in the Magento Connect console) and now I am getting an invalid PHP version error (says I need PHP 5.3.0 or newer). I have run phpinfo and I am getting 5.2.6 as the installed version.
This makes no sense at all, as the test store is running just fine with 5.2.6.
Anyone have any ideas?
Best Answer
The system requirements for version 1.9 are PHP5.4 or 5.5 You will have to update you current server to the newer version of PHP. In addition you will get a performance boost by going with PHP5.4 or higher
SYSTEM REQUIREMENTS FOR MAGENTO ENTERPRISE EDITION 1.14.1 AND COMMUNITY EDITION 1.9.1
Magento requires a LAMP or LNMP stack
Operating System Linux x86-64
Web Server Apache 2.x Nginx 1.7.x
Database MySQL 5.6 (Oracle or Percona)
PHP PHP 5.4 PHP 5.5
SSL A valid security certificate is required for HTTPS. Self-signed SSL certificates are not supported. SUPPORTED TECHNOLOGIES
Redis REDIS can be used for session or cache storage
Memcached Memcached can be used for session or cache storage (EE Only)
Apache Solr SOLR SEARCH can be used as a search provider
http://magento.com/resources/system-requirements