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

Risk of Rain 2 Co-op Won't Connect? Here's the Fix

Most 'Risk of Rain 2 multiplayer not working' cases are a modded/version mismatch or a strict NAT blocking the P2P connection. The fastest fix in 2026: if you use mods, both players run the identical mod set (easiest with r2modman profiles), then the host invites through the Steam overlay rather than the lobby browser.

Risk of Rain 2 — the version-string trap

#1 cause of 'can't join'
Mods change your version string to 'MODS' instead of 1.3.x — disable mods or use one that restores the version, all players must match
Quick fix
Both host and client fully restart the game (kill from Task Manager); confirm Steam is not in Offline Mode
Public-lobby fix
Enabling crossplay resolves many public-lobby connection failures

Last verified: September 2026

Error codes

Kicked instantly / 'mod mismatch' The client's mods don't match the host's

Cause: Different mods or versions between players (BepInEx/R2API).

Fix:
  1. Both players use r2modman and share the exact same profile (Export/Import code).
  2. Ensure BepInEx and R2API versions match on both machines.
  3. For a quick vanilla game, both disable mods and verify files.
Can't join friend / connection failed The P2P connection never establishes

Cause: Strict NAT, firewall, or Steam relay blocked.

Fix:
  1. Host invites via the Steam overlay (Shift+Tab > Join Game) instead of the in-game browser.
  2. Allow Risk of Rain 2 through the firewall on both PCs.
  3. If on a restrictive network, try a home connection or hotspot; enable UPnP on the router.

Fixes that work for most Risk of Rain 2 errors

  1. Match mods exactly with r2modman shared profiles (or both go vanilla).
  2. Host invites through the Steam overlay, not the lobby list.
  3. Verify game files on both PCs after an update.
  4. Allow the game through the firewall; enable UPnP for strict NAT.
  5. Set the lobby type to Friends or Public explicitly.
  6. Restart Steam (online) before hosting.

FAQ

Why does Risk of Rain 2 kick me when I join my friend?

It's almost always a mod mismatch — different mods or BepInEx/R2API versions between players. Use r2modman and import the host's exact profile, or both play vanilla with verified files.

How do I fix 'can't join friend' in Risk of Rain 2?

Invite through the Steam overlay rather than the in-game browser, allow the game through the firewall on both PCs, and enable UPnP on your router if your NAT is strict.

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