On a server, AddonsLib matters because registration happens once, at startup, and every client must agree with the server about which blocks exist. A mismatch causes kicked players, ghost blocks, or blocks that vanish on relog.
Match client and server exactly
1. Build one mods folder containing AddonsLib and all dependent content mods.
2. Distribute that exact folder to every player — same files, same versions.
3. Start the server and read the log for registration errors before inviting anyone in.
Test before opening
Join with a vanilla-plus client that has the same mods and place a bridge, a roof, and a fence from each content mod. Walk away and back to confirm they persist. If a block disappears for one player but not another, that player's content mod version differs — have them reinstall from the shared folder.
Handle updates carefully
When you update any content mod, update AddonsLib at the same time and push the new folder to everyone before restarting. Never update the library alone mid-season; a newer library with older content mods is the most common cause of missing blocks on servers. Announce the update, take a backup of the world, then restart.
