I did not manage to do the OH upgrade and stayed with version 2.5.0. Can I somehow upgrade some bindings by hand? You can’t use Paper UI - it takes forever to install.
Generally you want to run the same version of add-ons and core. There are breaking changes that occur from time to time which makes it so that the add-ons will not work on an earlier version of OH.
If you plan on keeping your core at 2.5.0 you can download the latest 2.5.12 add-ons kar file and put that into your addons folder. When that file is present the add-ons get installed from it.
OH 3 add-ons are not compatible with OH 3 so as far as you can go is 2.5.12 which is already half a year old now.
One purpose of 2.5.1 was to permit bindings & core to have different versioning, if I recall correctly
It is possible the 2.5.12 kar file might not work without updating to 2.5.12 but most all the changes were in bindings.
That’s right, it didn’t happen in 2.5.0. So indeed OP will need to upgrade in order to run the 2.5.12 binding.
However, this is really low risk because there were no changes to openHAB core between version 2.5.0 and 2.5.12, only changes to bindings. The only change made in 2.5.1 was to add the ability to run versions of 2.5.x bindings different from the OH core verison.