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Networkcrash

Failed to verify protocol / server sent invalid data

Also seen as: failed to verify protocol server sent invalid data protocol mismatch FiveM bad protocol version

What causes it

The client and server protocol/build don't match, or the connection was corrupted. Often an outdated client, outdated server artifacts, or a network issue mid-handshake.

How to fix it

Update both client and server to current versions and retry.

  1. Client: ensure FiveM is fully updated.
  2. Server: update to current recommended artifacts.
  3. Retry the connection; transient network issues can cause this once.
  4. If persistent, check for a proxy/firewall interfering with the connection.

Related errors

native (0x...) isn't supported / resource can't runServer connection timed out / failed to connect after 3 attempts

Related guides

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