Hey. I just updated to my server 1.12.1 and got now this error:
[00:47:00] [Server thread/WARN]: [Multiverse-Core] Failed to set the generator for world '173pre' to '173generator': java.lang.NoSuchMethodError: org.bukkit.configuration.file.YamlConfiguration.loadConfiguration(Ljava/io/InputStream;)Lorg/bukkit/configuration/file/YamlConfiguration;
[00:47:00] [Server thread/WARN]: [Multiverse-Core] This is a bug in the generator plugin, NOT a bug in Multiverse!

Also got this error: https://one.denizenscript.com/paste/44423

Any ideas ?

Looks like bukkit/spigot API change broke my plugin. This is the first time since forever where I see bukkit API introducing a breaking change. The fix is probably very simple, but I'm not actively working on this plugin anymore.

And also I feel like this is a very stupid thing to break in bukkit/spigot API, in previous versions they did insane stuff to avoid breaking plugins even when Minecraft did a fundamental change. And now they just removed a method because it didn't p[roperly deal with encoding?

At the tim I wrttye the code and last time I compiled it, the method wasn't even deprecated.

And as I said, I'm not going to try to fix it again. There is a good reason I made it use - at that time - non-deprecated bukkit API only.