How to Fix a Medieval MC [FABRIC] MMC1 Server That Keeps Crashing
Medieval MC [FABRIC] MMC1 is one of several separate editions the Medieval MC team publishes side by side. Most connection crashes trace to a player being on a different edition's client, not an actual mod conflict.
See the Medieval MC [FABRIC] MMC1 pack page for sizing before you chase anything else.
1. A player on the wrong edition
FORGE, MMC1, MMC2, MMC3, MMC4 (Fabric/NeoForge variants) are all separate Medieval MC releases — none of them interoperate. If a connection throws a mod-list mismatch, the fix is almost always reinstalling the exact MMC1 client from CurseForge rather than debugging mods.
2. RAM on both ends
Medieval MC is resource-heavy. Size the server generously, and remember a player's own client needs real headroom too — at least 6 GB is the commonly reported floor — since a client-side crash can look identical to a server problem.
3. The right Java version
Match the Java release the pack specifies exactly. A mismatched JDK is an easy-to-miss startup-crash cause that has nothing to do with the mod list itself.
FAQ
Is MMC1 the same as the Medieval MC [FORGE] edition?+
No — Medieval MC publishes separate, non-interoperable editions: FORGE, MMC1/MMC2/MMC3 on Fabric, MMC4, and MMC5 on NeoForge. A client built for one edition can't join a server running another, and the resulting error reads like a mod conflict.
My friend gets a mod mismatch error — what should they check first?+
Confirm they installed Medieval MC [FABRIC] MMC1 specifically from CurseForge, not an older Modrinth mirror or a different numbered edition. This single check resolves the large majority of reported connection crashes.
Host Medieval MC MMC1 on the matching edition every time
CoalHost installs the exact Medieval MC edition you choose, so a client on the wrong release is never the server's fault.
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