Look for duplicate or incompatible dependencies. If the addon conflicts with another, try:
Download the (.jar) for 1.21.1 from the AntiCope GitHub Releases . Locate Mods Folder :
The add-on attempted to register the global command Meteor.sync , which is a reserved namespace currently used by the core engine.
: While 1.21.1 is widely stable, developers are actively tracking bugs for newer versions like 1.21.8 and 1.21.10. Finding and Installing : The official source is the Meteor Rejects GitHub Releases Installation : Download the file and place it into your Minecraft folder alongside the base Meteor Client jar. Troubleshooting
The development team rejected the proposal based on several key factors: