If you have a working MythTV setup, and you want to try a newer version, both the software, and the database, need upgrading.
Usually, a newer version of the software will handle this automatically – even creating a database backup beforehand.
If you haven't upgraded in a long time, however, there might be problems. e.g. the program might say:
Your database version is too old to upgrade with this version of MythTV. You will need to use mythtv-setup from MythTV 0.22, 0.23, or 0.24 to upgrade your database before upgrading to this version of MythTV.
Finding your current version
Most mythtv programs give some useful information if you use the -version argument:
$ mythbackend --version Please include all output in bug reports. MythTV Version : 17686M MythTV Branch : branches/release-0-21-fixes Library API : 0.21.20080304-1 Network Protocol : 40 Options compiled in: linux release using_oss using_alsa using_arts using_jack using_backend using_dbox2 using_directfb using_dvb ...
% ./MythFrontend --version Please attach all output as a file in bug reports. MythTV Version : Unknown MythTV Branch : branches/release-0-23-fixes Network Protocol : 23056 Library API : 0.23.1.201000710-1 QT Version : 4.6.0 Options compiled in: release darwin_da using_corevideo using_backend using_darwin using_firewire ...
but that doesn't help you to understand the database, or plugins.
MythTV schemas and protocols
|0.21||1214||40||Combined MythDVD into MythVideo||1013||1016|
|0.22||1244||50||Oldest version that current software can upgrade||1017||1028|
|1299||72||Combined MythVideo into core MythTV||1019|
|29-fixes||29||1348||91||Yes, really 29!||1024|
|master||30-Pre||1348||91||Current as at Jul 26, 2017||1024|
If your current setup is older than 0.22, you will have to do a staged upgrade — first to 0.22, then to 0.28, or the lastest (master, or someone's experimental branch).
Note that the database schemas for the plugins usually don't change as often.
KnoppMyth was a minimal Linux distribution for just creating a MythTV computer. This author (Nigel) would never have done any MythTV development if not for a fast and easy way to build a machine. It was replaced by a different distribution — LinHES — back in 2009.
This table lists many beta and final versions of KnoppMyth. Of limited use now, but just in case:
Towards the end, a nice graphical setup tool — MythVantage — was produced. This lives on, in LinHES:
Information about LinHES releases (and KnoppMyth naming) is here.
For a while, a team was also producing customised Ubuntu releases that installed a stripped down Linux with MythTV. They also had a graphical management tool — Mythbuntu-Control-Centre.
Sadly, Mythbuntu has stopped being upgraded and supported. Read this.