# nw_quic_set_application_error(_:_:_:) Sets the QUIC application error code to send for the connection. ``` func nw_quic_set_application_error(_ metadata: nw_protocol_metadata_t, _ application_error: UInt64, _ reason: UnsafePointer?) ``` ## Parameters `metadata` A QUIC protocol metadata instance. `application_error` A QUIC application error code. `reason` An error reason string. ## Discussion --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)