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Fix "mismatched mod channel list" and mod mismatch errors

2 min readUpdated Nov 3, 2026Copy link

The player's mods don't match the server's. The fix is to make both sides run the same modpack and loader version, not to change server settings.

The player is disconnected while joining with one of these:

Connection closed - mismatched mod channel list

Incompatible client! Please use NeoForge 21.1.191

Newer Forge shows a table instead: "Your client is missing the following mods, install these mods to join this server", "The server is missing the following mods, remove these mods from your client to join this server" or "The following mod versions do not match". Older Forge says "Mod rejections" or "Fatally missing registry entries".

Why it happens #

Forge and NeoForge compare the mods on both sides when a player connects. Mods that add content must exist on both sides, at compatible versions. The join fails when:

• The player has a different modpack version than the server (the pack updated on one side only).
• A mod was added or updated on the server but not given to players, or the other way round.
• The loader version differs. "Incompatible client! Please use NeoForge …" names the exact NeoForge version the server runs.
• The player added extra content mods that the server doesn't have.
• Wrong Minecraft version entirely; that usually shows as Outdated client/server instead.

How to fix it #

1. Read the message: it names the mods (or loader version) that differ. The full list is in the player's logs/latest.log when the screen cuts it short.
2. Check the server's list. On ESN, open Files → mods to see exactly which jars and versions the server runs.
3. Line up the modpack version. In the CurseForge app, Modrinth app or your launcher, set the client pack to the same version as the server pack. Mixing version 1.2 on one side and 1.3 on the other is the most common cause.
4. Match the loader. Install the NeoForge or Forge version the message names, or update the server to match the clients. Back up first.
5. Remove extras from the player's game that the server doesn't have, unless they are client-only (minimaps, shaders, HUDs), which are fine.
6. Share one source of truth. Give players a link to the exact pack version, or a zip of the server's mods folder minus server-only mods.

What about Fabric? #

Fabric itself doesn't compare mod lists when you join. A mismatch there tends to show up later, as a disconnect with a decoding error or missing registry entries once the client meets content it doesn't know. The fix is the same: same mods, same versions, same Minecraft version on both sides. Fabric API must be present on both.

Updating a modpack safely on ESN #

1. Stop the server and download a copy of the world (see backups).
2. Download the new official server pack for your pack version.
3. Replace the mods folder (and config if the pack says to) with the new one, using Files or SFTP.
4. Start the server, check the console, then tell players which pack version to install.

Removing a mod that added blocks or items deletes them from the world, so read the pack's changelog first.

FAQ #

Can I join a modded server with extra client mods?

Client-only mods like minimaps, shaders and HUD mods are usually fine. Mods that add blocks, items or mobs must be on both sides.

Why does it ask for a specific NeoForge version?

The server checks the loader version too. Install that exact NeoForge version in your launcher profile, or update the server to match.

Does deleting a mod from the server break the world?

Blocks and items from that mod disappear from the world. Back up before removing content mods.

Sources: Forge source: mod mismatch screen messages (checked Nov 3, 2026) · Minecraft language file: Incompatible client message (checked Nov 3, 2026)

Still stuck? Use the live chat on the panel or ask in the ESN Systems Discord. Last updated November 3, 2026.