REVIEW THE GUIDELINES - see Contributing link on right side.

Minecraft version: 1.12.2
Galacticraft version ("latest" is not a valid option): 1.12.2-4.0.2.261

Single player (SP), Multiplayer (MP), or SP opened to LAN (LAN)? SP

• If MP server, please mention if it has Sponge, AtomMC, BukkitForge, BungeeCord etc.

Any Galacticraft add-ons installed? Please list all of them: More-Planets-1.12.2-2.1.14-CG261 and MorePlanetsExtras-1.12.2-1.0

Please upload crash report / full log to Github Gist or any other paste site: https://pastebin.com/zRVaP6fL

Please provide screenshots / videos / full modlist as needed!
Capture

Please state the site that you downloaded Galacticraft from: micdoodle8.com

you have the dev jar versions of the galacticraft mods and micdoodlecore. Please use the non-dev jars

That fixed the issue. Thank you!