As described in a previous blog article Stubbles did not work on PHP versions built using libxml 2.7, which is the case for at least all PHP versions since 5.3.0. We fixed the issue and make it today available as a bugfix release. This means that both 1.3.1 and 1.4.1 can now be used on PHP 5.3. See the changelog for a complete list of changes. Additionally we started to provide an Upgrade Guide with more detailed instructions on what needs to be done when upgrading from a previous version.