🎮 Game Error Codes What it means & how to fix it

Monster Hunter World Can't Connect to a Session? Here's the Fix

Most Monster Hunter World multiplayer failures come from a strict NAT type, the game being blocked by your firewall, or trying to join a session that's full or quest-locked. The fastest fix: set an Open NAT (enable UPnP), allow MonsterHunterWorld.exe through the firewall, and join via a shared Session/Squad ID rather than searching. Remember most quests need you to watch the intro cutscene before you can join. Steps below, in order.

Monster Hunter: World — ports & session-type fix for join errors

Ports to forward (TCP)
27015-27030, 27036-27037
Ports to forward (UDP)
4380, 27000-27031, 27036
Steam matchmaking ping
Steam > Settings > In-Game > set matchmaking browsing ping to 250 to widen the session pool
Gotcha
story quests are gated — you can't freely join a friend mid-story-quest (5038f/50382-MW1); use an SOS flare or matching quest progress

Last verified: September 2026

Error codes

Failed to join session / session is full You couldn't enter your friend's online session

Cause: Strict NAT, the session being full (16 players max), or a quest that's already in progress and locked.

Fix:
  1. Have the host share the Online Session ID (Communication > Online Session > invite/ID) and join by that ID.
  2. For quests, the host must post the quest and you join before it starts, or use an SOS flare mid-quest.
  3. Confirm the session isn't full (16-player cap) and the host set it to allow friends/anyone.
  4. Set NAT to Open so peer connections can be brokered.
Communication error / connection lost The online connection dropped or couldn't be established

Cause: Strict/Moderate NAT, firewall blocking, or an unstable connection.

Fix:
  1. Enable UPnP on your router or forward the game's ports for an Open NAT type.
  2. Allow MonsterHunterWorld.exe through Windows Firewall and antivirus.
  3. Use a wired connection and restart your router to refresh NAT.

Fixes that work for most Monster Hunter World errors

  1. Set an Open NAT: enable UPnP on the router (or forward the ports) — strict NAT is the #1 cause of MHW connection failures.
  2. Allow MonsterHunterWorld.exe through Windows Firewall and any antivirus.
  3. Join via a shared Online Session ID rather than random search to land in the same session reliably.
  4. For quests, watch the intro cutscene once so you can join others' quests; the host posts and you join before start, or fire an SOS flare.
  5. Confirm the session isn't at the 16-player cap and is set to accept friends.
  6. Use a wired Ethernet connection and restart the router to clear a stale NAT.
  7. Verify game files (Steam) if you get communication errors after an update.

FAQ

Why can't I join my friend in Monster Hunter World?

Most often it's a strict NAT type or the quest is already locked. Set an Open NAT via UPnP, allow the game through the firewall, and join using the shared Online Session ID.

How do I fix strict NAT in MHW?

Enable UPnP on your router, or manually forward the game's ports to your PC, then use a wired connection. An Open NAT lets the peer session connect reliably.

Why can't I join a quest that's already started?

MHW locks most quests once they begin. Either join before the host starts, respond to their SOS flare, or have them re-post the quest so you can join at the start.

What's the player limit in a MHW session?

An online session holds up to 16 players, but individual quests are limited to 4 hunters. A full session will reject new joins until someone leaves.

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