Fixes · 6 min read
Players can't join your modded Minecraft server? Match the mods
What mismatched mod channel list, missing mods and unknown registry entries mean on a NeoForge, Forge or Fabric server, and how to match the two sides.
Last checked
Short answer
Find your message
The wording below is the loaders' own. It changes a little between loader versions, so match on the key words.
| What the player sees | What it means | Check |
|---|---|---|
| Your client is missing the following mods, install these mods to join this server | What it meansThe server has mods the player's game lacks (Forge, NeoForge) | Check2 |
| The following mod versions do not match, install the same version of these mods that the server has | What it meansBoth sides have the mod, at different versions (Forge, NeoForge) | Check2 |
| The server is missing the following mods, remove these mods from your client | What it meansThe player has a mod the server lacks (Forge, NeoForge) | Check3 |
| Connection closed - mismatched mod channel list | What it meansThe two mod lists differ (Forge, up to Minecraft 1.20.1) | Check2, 3 |
| Channel of mod “…” failed to connect: This channel is missing on the client side, but required on the server! | What it meansThe server has a mod the player lacks (NeoForge). With the sides the other way round, the player has the extra mod | Check2, 3 |
| Received … registry entries that are unknown to this client. This is usually caused by a mismatched mod set between the client and server. | What it meansThe server has content from mods the player lacks (Fabric) | Check2 |
| You are trying to connect to a server that is running NeoForge, but you are not. Please install NeoForge Version: … | What it meansThe player started plain Minecraft, or another loader | Check1 |
| In the server list: Incompatible FML modded server, or Server mod list is not compatible | What it meansThe same mismatch, seen before joining (Forge, NeoForge) | Check1, 2 |
| In the server list: Forge (or NeoForge) server network version is outdated, or client network version is outdated | What it meansThe two sides run different loader versions | Check1 |
| Incompatible client! Please use 1.21.1 (or Outdated client!, Outdated server!) | What it meansThe player's Minecraft version differs from the server's | Check1 |
| Connection timed out, Connection refused, or not white-listed | What it meansThe mods are fine. It's the address, the server's state or the whitelist | Check5 |
When the list is long, Forge and NeoForge shorten it and add see latest.log for the full list. That file is in the logs folder of the player's game.
1. Same loader, same Minecraft version
Start with the two things every mod depends on. The server runs one loader (NeoForge, Forge or Fabric) on one Minecraft version, and each player's game has to be that loader on that version. A player who presses Play on plain Minecraft, or opens a pack built for another loader, is turned away before the mods are even compared.
The loader has a version of its own as well. A pack names the one it was built with, and a launcher that installs the pack installs that loader version with it. If the server list says a network version is outdated, put both sides on the loader version the pack names.
For a pack on Modrinth, the modpack server sizer shows its loader and Minecraft version from the pack's link, for each version of the pack.
2. The player is missing mods, or has other versions
This is the common one. The fix is for the player to install the same pack, at the same pack version, that the server runs. Matching mods one at a time works too, but it's slow and easy to get wrong.
The two sides usually drift apart in one of three ways:
- The pack was updated on one side. A launcher can move a player to the pack's newest version while the server stays where it was, or the server was updated and the players weren't. Pick one pack version and put everyone on it.
- Mods on the server were updated one by one. The server then has newer mods than the pack gives its players. Each player needs those same versions.
- A mod was added to the server after the pack. Unless it works on the server alone, every player needs it too, at the same version.
3. The player has mods the server lacks
Mods that only change what a player sees, such as minimaps and shaders, are normally accepted, because the server never needs to know about them. A mod that adds blocks, items or creatures has to be on both sides. Either add it to the server at the same version, or take it out of the player's game. The message names the mod.
4. Read both logs
If the screen is vague, the logs say more. On the player's side, open latest.log in the game's logs folder and look at the last lines before the disconnect. On the server, watch the console while the player tries to join: a refused player is usually named there with the reason. Forge up to 1.20.1 writes Terminating connection with client, mismatched mod list.
5. When the mods are fine
Connection timed out, Connection refused and You are not white-listed have nothing to do with mods. First make sure the server finished starting: a modded server can take minutes, and nobody can join until its console prints Done. Then work through can't connect to your Minecraft server, which covers the address, the whitelist, firewalls and port forwarding.
On our servers
- The Mods tab shows the loader and Minecraft version at the top, and which modpack and pack version the server was installed from. Send your players that name and version.
- Installed lists every mod file on the server, including files uploaded over SFTP, with the version of each one Modrinth recognises. Compare it with a player's mods when one message names a single mod.
- Version & loader shows the loader, the Minecraft version and the Java under Runs now. On a Fabric server, the loader's own version is Fabric Loader Version under Game → All settings → Startup settings.
- The console is on the Overview. Type the player's name into Search the console to find the line that turned them away.
- Copy the Join address from the Overview, and under Can players reach it? press Run the checks. If it answers there, the server is up and the difference is in the player's game.
Setting a pack up from the beginning? How to put a modpack on a Minecraft server goes through it step by step.
Still stuck?
On our servers, press Contact a human on your server's page. Paste in the exact words the player sees, with the pack name and version they installed. A person reads every request.
Wording checked on 12 November 2026 against Forge 1.20.1 and 1.21.1, NeoForge 1.21.1 and its current release, and Fabric API for 1.21.1 and its current release.