.29 Mythlight Frontend does not work with .30 Backend

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jac1d
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.29 Mythlight Frontend does not work with .30 Backend

Post by jac1d » Fri Apr 05, 2019 5:16 pm

This is more a confirmation of information than a question. I did some quick googling and looking around the forum and I couldn't see a clear answer so I took a swing at booting my .29 Mythlight Pi3 frontend after a (shockingly smooth) upgrade of my LinHES based .29 backend to the new LinHES 8.6 release (Mythtv .30 + fixes).

The startup of the (Pi Mythlight .29) Frontend errors due to a database schemea mismatch (mine was something along the lines of the FE being 1348 and the BE being 1350). Perhaps unsurprising but worth knowing before you embark on a multi-machine household upgrade, in case you get caught in the middle with an angry family. :)

I intended to do a fresh install of the .30 Mythlight packages from scratch and thoroughly document everything to include all the recent learnings about getting everything working with my setup so will proceed with that this morning. Will post those details once complete to give back to the community that has been so helpful to me with Myth over the years.

-Jeff

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pgbennett
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Re: .29 Mythlight Frontend does not work with .30 Backend

Post by pgbennett » Sat Apr 06, 2019 4:54 pm

MythTV expects the frontend and backend to be the same major version. This is not a raspberry pi specific issue, that is also the case with any linux setup. That should probably be spelled out in the wiki, but I am not sure if it is.

jac1d
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Re: .29 Mythlight Frontend does not work with .30 Backend

Post by jac1d » Sat Apr 06, 2019 7:05 pm

I had a feeling (and vague recollection) that it was the case that the FE and BE versions always had to match, but you are correct, I wasn't able to find explicit confirmation of that anywhere so I wanted to post something for others searching to find. This is important for users who have multiple FE and want to embark on an upgrade, it changes the quantum of risk and required timeline in a busy household.

It would be interesting to potentially support basic features with a version or two mismatch as well where possible, but that may be too much to ask of the developers as they refactor things.

-Jeff

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pgbennett
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Re: .29 Mythlight Frontend does not work with .30 Backend

Post by pgbennett » Sat Apr 06, 2019 7:24 pm

See my proposed and rejected change to allow a version mismatch:
https://code.mythtv.org/trac/ticket/13261
and
https://lists.gt.net/mythtv/dev/617305#617305

jac1d
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Re: .29 Mythlight Frontend does not work with .30 Backend

Post by jac1d » Mon Apr 08, 2019 5:21 pm

Excellent background, thanks for sharing the link.

The final poster there makes a really good point:

"Further clarification: I'm still very much in favor of converting
nearly all frontend interaction with the backends to use API calls
*and* to begin supporting some backward compatibility there."

However, given the maturity of Myth, it seems like diminishing returns to refactor everything to use an API like that at this point.

I need to catch up on what the roadmap includes, it's quite incredible the level of maturity and features the project has reached and that it is still going so strong after 16 years and major technological and business model changes in the video world.

-Jeff

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