What Packet Fixer works with.
| Platform | Java Edition |
|---|---|
| Loaders | Fabric, Forge, NeoForge, Quilt |
| Minecraft versions | 1.12.2, 1.16.5, 1.18, 1.18.2, 1.19.4, 1.20.1, 1.20.6, 1.21.1, 1.21.11, 26.1, 26.2, 26.3 |
| Environment | Client, Server |
Packet Fixer is a Minecraft Java mod that raises the packet, NBT, and payload size limits vanilla Minecraft enforces, so mod-heavy servers stop disconnecting players over oversized data instead of an actual crash or exploit. TonimatasDEV built it for modpacks that push past vanilla's networking ceiling, and it now ships for Fabric, Forge, NeoForge, and Quilt under the MIT license.
Errors Packet Fixer resolves
These are the exact disconnect and console errors the mod's own documentation lists as fixed:
- Tried to read NBT tag that was too big; tried to allocate: X bytes where max allowed: 2097152
- Badly compressed packet - size of X is larger than protocol maximum of 2097152
- Attempted to send packet over maximum protocol size: 8388608
- Chunk Packet trying to allocate too much memory on read
- Packet too big (is X, should be less than 8388608)
- Payload may not be larger than 1048576 bytes / Payload may not be larger than 32767 bytes
- Packet too large: size X is over 8, Length wider than 21-bit, Unable to fit X into 3
- Connection timeout, VarLong too big, VarInt too big
Installing Packet Fixer on Fabric, Forge, NeoForge, and Quilt
The mod's own listing states it is required on both the client and the server, not just one side. Every player and the server need it installed together for the packet and NBT limits to actually change, since a mismatched pair still hits vanilla's ceiling on whichever side is missing it.
- Fabric: 1.16.5 through 26.3, current release build 3.3.6 published 2026-09-15
- Quilt: 1.16.5 through 26.3, current release build 3.3.6 published 2026-09-15
- NeoForge: 1.18 through 26.3, current release build 3.3.7 published 2026-09-20
- Forge: 1.12.2 through 1.20.6, capped there since the last Forge update on 2026-04-04
Dependencies and modpack use
Every current Fabric, Quilt, NeoForge, and Forge build lists no required dependencies, so it drops into a modpack without pulling in Fabric API or another library. Only the legacy 1.12.2 Forge build, last released in 2025, needs MixinBooter alongside it. TonimatasDEV's project page also notes the mod is safe to include just to raise a pack's networking headroom, even in packs that never hit the errors above.
Downloading and installing Packet Fixer
Frequently asked questions
Questions about Packet Fixer.
5 questions
Which packet errors does Packet Fixer fix?
It targets oversized-data disconnects like packet too big, badly compressed packet, payload may not be larger than 1048576 bytes, NBT tag too big, VarInt or VarLong too big, and connection timeouts caused by those oversized packets. These come from the mod's own documented list, not a general description.
Do I need to install Packet Fixer on the client, the server, or both?
Both. The mod's listing states it is required on client and server together. Installing it on only one side leaves the other side enforcing vanilla's packet and NBT size limits, so the errors can still happen.
Does Packet Fixer support Forge?
Yes, but Forge is behind the other loaders. Forge builds cover 1.12.2 through 1.20.6, and the newest Forge release (2026-04-04) only declares support up to 1.20.4, so a 1.20.5 or 1.20.6 server needs an older build. Fabric, Quilt, and NeoForge all reach 26.3.
Is Packet Fixer the same mod as ModPacketFix?
No. Packet Fixer is TonimatasDEV's Fabric, Forge, NeoForge, and Quilt mod on Modrinth. ModPacketFix is an unrelated SpigotMC plugin with a similar name; check the platform and loader before downloading either one.
Does Packet Fixer require Fabric API or another dependency?
No. Every current build across all four loaders lists no required dependencies. Only the discontinued 1.12.2 Forge build, last updated in 2025, needs MixinBooter installed alongside it.
