Describe the bug
When I right-click on a global skin library block, the skin should appear, but when I click join, [Java 8 Update 51] pops up as My Java and causes a bug. My Java version is [Java 8 Update 291] and I also tried [Java 8 Update 301] but failed. I have used this mode with other modes. It was good at first, but there was an error with other modes, so I erased other modes and opened the library block of this mode, and this error occurred. I erased this mode and tried to install it, but it failed.

I saw the video here. And I followed the way in this video. However, while playing the game, the connection to the game is terminated, causing a bug. Is there any other solution?

-This error has been in this state for a long time.

Sorry, 1.7/1.12 is no longer supported

And not a bug, you need change java version in the minecraft launcher