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0x11

VERSION_NEGOTIATION_ERROR

RFC 9000 §20

QUIC VERSION_NEGOTIATION_ERROR (0x11) is sent when a QUIC version negotiation attempt fails. Defined in RFC 9368 (QUIC Version Negotiation). Client and server could not agree on a compatible QUIC version after attempting the version negotiation protocol.

Code

0x11

Decimal

17

Standard

RFC 9000 §20

Description

QUIC version negotiation (RFC 9368) allows client and server to agree on a QUIC version when the client's initial version is not supported by the server. The server sends a Version Negotiation packet listing its supported versions. The client then retries with a compatible version. VERSION_NEGOTIATION_ERROR occurs when this process fails: the client retries with a version but the negotiation parameters are inconsistent, or the retry packet does not comply with the version negotiation specification. This code is separate from the scenario where the server sends a Version Negotiation packet and the client has no compatible version – in that case the connection simply fails at the application layer. VERSION_NEGOTIATION_ERROR is specifically for violations of the version negotiation protocol itself, not for the case of having no common version.

Common Causes

  • Version negotiation retry packet does not comply with RFC 9368
  • Incompatible version_information transport parameters
  • Client retried with a version that does not match the negotiation outcome