DaemonUmbra

Please provide debug.log for both client and server

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Delete C:\Users\kikis\AppData\Roaming\.minecraft\config\fml.toml and try again

Full installer log please?

Delete forge-common.toml from your config folder

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

This is where Google would come in handy, specifically a search for "Java Profiler"

If you have any more problems just make a thread, we don't give support via DMs

Same error, different config... at this point if you haven't made any config changes just delete the whole config folder

If that didn't work please provide the new debug.log that will have generated

Delete C:\Users\caspe\AppData\Roaming\.minecraft\config\Mekanism\client.toml and try again

You make a GitHub account, then return to gist

GIST... the first one in the list!!!

I highly doubt you managed to max out gist...

Click the thing that says "Reveal hidden contents", then the other one that is under the "Logs" heading

Please use one of the paste sites listed in my signature

JVM args are in the Installation settings, under Advanced Options or whatever it calls them, just put that on the end

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

This is too vague for us to really provide any meaningful assistance. Your best bet would be to run a profiler and provide the report.

Really old Minecraft versions are no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Whose bright idea was it to log the config debug messages at TRACE? Add -Dforge.logging.debugFile.level=TRACE to your JVM arguments and try again, then provide debug.log when it crashes (This doesn't fix it, it puts more info to the log)

Also, when you don't get a response within 3 minutes, have patience instead of making a second identical thread