Kamailio SIP Server v4.0.7stable is out – a minor release including fixes in code and documentation since v4.0.0 – configuration file and database compatibility is preserved.
Kamailio (former OpenSER) v4.0.7 is based on the latest version of GIT branch 4.0, therefore those running previous 4.0.x versions are advised to upgrade. There is no change that has to be done to configuration file or database structure comparing with older v4.0.x.
Note that branch 4.0 is now the 3rd old stable branch. The latest stable branch is 4.2, at this time having release of v4.2.0 out of it. For the future, the project is focusing on maintaining the last two stable branches, at this moment being 4.2 and 4.1.