The RTCError interface describes an error which has occurred while handling WebRTC operations. It's based upon the standard DOMException interface that describes general DOM errors.

RTCError()

Creates and returns a new RTCError object initialized with the different parameters and, optionally, a string to use as the value of the error's message property.

In addition to the properties defined by the parent interface, DOMException, RTCError includes the following properties:

errorDetail Read only

A string specifying the WebRTC-specific error code identifying the type of error that occurred.

receivedAlert Read only

An unsigned long integer value indicating the fatal DTLS error which was received from the network. Only valid if the errorDetail string is dtls-failure. If null, no DTLS error was received.

sctpCauseCode Read only

If errorDetail is sctp-failure, this property is a long integer specifying the SCTP cause code indicating the cause of the failed SCTP negotiation. null if the error isn't an SCTP error.

sdpLineNumber Read only

If errorDetail is sdp-syntax-error, this property is a long integer identifying the line number of the SDP on which the syntax error occurred. null if the error isn't an SDP syntax error.

sentAlert Read only

If errorDetail is dtls-failure, this property is an unsigned long integer indicating the fatal DTLS error that was sent out by this device. If null, no DTLS error was transmitted.

In this example, a handler is established for an RTCDataChannel's error event.

dataChannel.addEventListener("error", (event) => {
  let error = event.error; // event.error is an RTCError

  if (error.errorDetail === "sdp-syntax-error") {
    let errLine = error.sdpLineNumber;
    let errMessage = error.message;

    let alertMessage = `A syntax error occurred interpreting line ${errLine} of the SDP: ${errMessage}`;
    showMyAlertMessage("Data Channel Error", alertMessage);
  } else {
    terminateMyConnection();
  }
});

If the error is an SDP syntax error—indicated by its errorDetail property being sdp-syntax-error—, a message string is constructed to present the error message and the line number within the SDP at which the error occurred. This message is then displayed using a function called showMyAlertMessage(), which stands in for whatever output mechanism this code might use.

Any other error is treated as terminal, causing a terminateMyConnection() function to be called.

The above example uses addEventListener() to add the handler for error events. You can also use the RTCDataChannel object's onerror event handler property, like this:

dataChannel.onerror = (event) => {
  let error = event.error;

  /* and so forth */
};