DaemonUmbra

If you can join the server then its not crashing. You as the host should not be trying to use the external IP to join, just use localhost to connect if you're on the same machine. For your friends it sounds like you need to forward your server's port.

Yes

First, take your server out of OneDrive. Second, please provide a screenshot of the server's mods folder that includes the address bar.

Please read the Logs section of my signature below and provide the appropriate log in the appropriate manner.

Why did you rename the server jar? Chances are file explorer is set to hide file extensions, whereas Java is expecting you to include the extension in your command.

As I told you before, 1.8 is not supported on this forum due to its age. Making a new thread that is exactly the same as the old one does not change this fact.

Read it again, but slowly

1.8 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

Do you know Java or any other programming language?

It sounds like you don't have Java installed

Have you tried completely reinstalling Java?

1.8.9 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

1.8.9 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

If the mods in question register Config GUIs, otherwise you'll need to do it the old fashioned way of editing text files and restarting your game

Please keep this forum in English. I would assume you are referring to mod config guis, which only work if you are using Forge version 1.14.4-28.1.56 or later with a mod that has a config gui.

Run the Jar manually, what happens?

That repo's not set up correctly, did McJty's tutorial go through that?

Old thread and you have no idea what you're talking about.

minecraft_server_1.12.2.jar will not start a Forge server, only the Forge jar will. WinRAR is naughty and takes control of any file extension that COULD be an archive, regardless of whether or not another program already controls that file extension. Run this once, then try running the Forge jar again.

Verify that you have Java installed. If you do have Java installed try running this then try the installer again.

1.7.10 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

What you translated it to isn't something I can understand. Can you provide the original message in text?

setupDecompWorkspace doesn't exist anymore, just import the MDK into your IDE

Saying what? Please provide a screenshot.

Remove Labymod and provide an unaltered debug.log