Should You Set online-mode=false?
Learn when online-mode=false is risky, when proxies may require backend offline mode, and how to avoid Minecraft username spoofing and UUID problems.
For a normal Minecraft Java server, you should not set online-mode=false as a quick fix.
What You Lose
With:
online-mode=false
the server no longer verifies official account sessions. That can create:
- Username spoofing.
- Permission abuse.
- Inventory/profile confusion.
- Whitelist and ban bypass risk.
- Plugin identity problems.
If players see Invalid Session, fix the session, launcher, or proxy forwarding problem. Do not remove authentication from a public server just to make the error disappear.
The Proxy Exception
Some Velocity or BungeeCord setups require backend servers to trust the proxy, while the proxy handles authentication. That is different from exposing an offline-mode server directly.
A safer proxy setup needs:
| Requirement | Why | | --- | --- | | Public players join only the proxy | Authentication happens there | | Backends are firewalled | Prevents bypass | | Forwarding mode is configured | Preserves identity | | Secrets/tokens match | Prevents spoofing | | Plugins are on correct layer | Avoids auth and permission confusion |
Private Offline Servers
Private offline-mode servers are still a risk. If you choose that route, understand that identity is now your responsibility, not the official session service's.
For most users, the right setting is:
online-mode=true
Read what online-mode does for the underlying behavior.
FAQ
Is online-mode=false safe?
Not for a normal public server. It disables official authentication and can allow username impersonation.
Why do some proxy networks use offline mode on backends?
Some proxy setups authenticate at the proxy and forward identity to backend servers. Backend servers must then be protected so players cannot join them directly.
Will online-mode=false fix Invalid Session?
It may bypass the symptom, but it weakens authentication. Fix session, launcher, or proxy configuration instead.
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