Leaving a Multiplayer Session

This guide explains how to properly leave a multiplayer session in Unreal Engine using the EOSCore plugin. Failing to clean up a session correctly can prevent players from joining new sessions or cause network conflicts.

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Critical Rule: Always Call DestroySession

You must always call the DestroySession node when leaving a session — whether by player choice, or disconnection.

Failing to do so will:

• Leave the session registered with Epic Online Services (EOS).
• Prevent the player from joining any new session until the game restarts.
• Cause "Session already exists" or "Join failed" errors.

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Where to Call DestroySession

The DestroySession node can be called from anywhere in your game:

• Player Controller (recommended for player-initiated leave)
• Game Instance (ideal for global cleanup)
• UI Widget (on "Leave Game" button press)

It does not matter where — only that it is called.

Important: What DestroySession does depends on who calls it. On a client it only removes the session locally, the host and the other players are not affected. On the host (the session owner) it removes the session from EOS, so it no longer shows up in searches. See Host Leaving below.

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Example Blueprint Flow

[Player Clicks "Leave Game"]
   ↓
DestroySession
   ↓ (On Success)
Open Level → "MainMenu"

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When to Call DestroySession

Scenario	Call DestroySession?
Player leaves via menu	Yes
Disconnected by host/kick	Yes
Network timeout	Yes
Returning to main menu	Yes

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Best Practices

1. Call on Level Transition:

   • Use Event End Play or On Destroyed in your Player Controller to ensure cleanup.

2. Handle Disconnections:

   • Bind to OnNetworkFailure or OnSessionFailure events to auto-destroy.

3. UI Feedback:

   • Show "Leaving session..." while DestroySession completes.

4. Error Handling:

   • Even if DestroySession fails, proceed to the menu, but log the error. The local session stays registered until it is destroyed or the game restarts, so call DestroySession again before creating or joining a new session.

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Common Issues

Problem	Cause	Fix
"Cannot join session"	Old session not destroyed	Call DestroySession
Stuck in "Joining..."	Session cleanup skipped	Add DestroySession on leave
Multiple sessions in EOS Dashboard	Players not cleaning up	Enforce DestroySession

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Notes

• Host Leaving: The rule above applies to players leaving. The host calls DestroySession only when the whole game ends, because it removes the session for everyone. To stop the match but keep the session, use EndSession instead.
• Testing: Use Standalone Game instances to verify cleanup in logs.

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Remember: DestroySession = Mandatory for clean session lifecycle.