[🐛 Bug]: [dotnet] Many WebSocketExceptions from BiDi if browser exits before disposal

[kevinoid]

Description

If the browser process exits before a BiDi is disposed (e.g. due to the user pressing close button, or due to an interrupt as in #16090 (comment)) , it causes many (infinite?) WebSocketExceptions to be logged.

Reproducible Code

using OpenQA.Selenium.BiDi;
using OpenQA.Selenium.Firefox;

using System;
using System.Threading;

using var webDriver = new FirefoxDriver(new FirefoxOptions()
{
    UseWebSocketUrl = true,
});

await using var bidi = await webDriver.AsBiDiAsync().ConfigureAwait(false);

Thread.Sleep(TimeSpan.FromSeconds(100));
// Kill browser process to produce WebSocketExceptions

Debugging Logs

1754428864215   geckodriver     INFO    Listening on 127.0.0.1:50968
1754428869404   mozrunner::runner       INFO    Running command: "C:\\Program Files\\Mozilla Firefox\\firefox.exe" "--marionette" "--remote-debugging-port" "50969" "--remote-allow-hosts" "localhost" "-no-remote" "-profile" "C:\\Users\\Kevin\\AppData\\Local\\Temp\\rust_mozprofileMW5401"
Read port: 50974
15:21:16.867 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake.
   at System.Net.WebSockets.ManagedWebSocket.ThrowEOFUnexpected()
   at System.Net.WebSockets.ManagedWebSocket.EnsureBufferContainsAsync(Int32 minimumRequiredBytes, CancellationToken cancellationToken)
   at System.Runtime.CompilerServices.PoolingAsyncValueTaskMethodBuilder`1.StateMachineBox`1.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TResult](Memory`1 payloadBuffer, CancellationToken cancellationToken)
   at System.Runtime.CompilerServices.PoolingAsyncValueTaskMethodBuilder`1.StateMachineBox`1.System.Threading.Tasks.Sources.IValueTaskSource<TResult>.GetResult(Int16 token)
   at System.Threading.Tasks.ValueTask`1.ValueTaskSourceAsTask.<>c.<.cctor>b__4_0(Object state)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
15:21:17.007 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The WebSocket is in an invalid state ('Aborted') for this operation. Valid states are: 'Open, CloseSent'
   at System.Net.WebSockets.WebSocketValidate.ThrowIfInvalidState(WebSocketState currentState, Boolean isDisposed, WebSocketState[] validStates)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsync(ArraySegment`1 buffer, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
15:21:17.124 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The WebSocket is in an invalid state ('Aborted') for this operation. Valid states are: 'Open, CloseSent'
   at System.Net.WebSockets.WebSocketValidate.ThrowIfInvalidState(WebSocketState currentState, Boolean isDisposed, WebSocketState[] validStates)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsync(ArraySegment`1 buffer, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
15:21:17.241 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The WebSocket is in an invalid state ('Aborted') for this operation. Valid states are: 'Open, CloseSent'
   at System.Net.WebSockets.WebSocketValidate.ThrowIfInvalidState(WebSocketState currentState, Boolean isDisposed, WebSocketState[] validStates)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsync(ArraySegment`1 buffer, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
15:21:17.372 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The WebSocket is in an invalid state ('Aborted') for this operation. Valid states are: 'Open, CloseSent'
   at System.Net.WebSockets.WebSocketValidate.ThrowIfInvalidState(WebSocketState currentState, Boolean isDisposed, WebSocketState[] validStates)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsync(ArraySegment`1 buffer, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
15:21:17.489 ERROR Broker: Couldn't process received BiDi remote message: System.Net.WebSockets.WebSocketException (0x80004005): The WebSocket is in an invalid state ('Aborted') for this operation. Valid states are: 'Open, CloseSent'
   at System.Net.WebSockets.WebSocketValidate.ThrowIfInvalidState(WebSocketState currentState, Boolean isDisposed, WebSocketState[] validStates)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsync(ArraySegment`1 buffer, CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at OpenQA.Selenium.BiDi.Communication.Transport.WebSocketTransport.ReceiveAsync(CancellationToken cancellationToken)
   at OpenQA.Selenium.BiDi.Communication.Broker.ReceiveMessagesAsync(CancellationToken cancellationToken)
...

[selenium-ci]

@kevinoid, thank you for creating this issue. We will troubleshoot it as soon as we can.

Selenium Triage Team: remember to follow the Triage Guide

[kevinoid]

For reference, I'm also able to reproduce the issue with Chrome and Edge. It is not Firefox-specific.

[Sahilghagg]

To solve this:

Always close or quit the browser driver gracefully using webDriver.Quit() or webDriver.Close() before disposing of the BiDi connection. This helps the browser and WebSocket to shut down properly.

Use proper async disposal patterns like await using or try-finally blocks to ensure the BiDi session and WebSocket are disposed even if exceptions occur.

Implement cancellation tokens and detect when the browser process exits or when the application is shutting down. Use these to cancel ongoing WebSocket receive loops and dispose resources cleanly.

Handle WebSocketException inside your message receiving loops to avoid flooding logs. These exceptions should be treated as expected signals when the connection is closed and can be logged as informational instead of errors.

Optionally monitor the browser process state to detect unexpected terminations and trigger cleanup earlier.

Code:

using var webDriver = new FirefoxDriver(new FirefoxOptions() { UseWebSocketUrl = true });
await using var bidi = await webDriver.AsBiDiAsync();

using var cts = new CancellationTokenSource();

try
{
await ProcessBiDiMessagesAsync(bidi, cts.Token);
}
catch (OperationCanceledException)
{
// Expected cancellation, can ignore or log
}
catch (WebSocketException wsEx)
{
Console.WriteLine($"WebSocket closed: {wsEx.Message}");
}
finally
{
webDriver.Quit();
}

async Task ProcessBiDiMessagesAsync(BiDiSession bidi, CancellationToken token)
{
try
{
while (!token.IsCancellationRequested)
{
var message = await bidi.ReceiveMessageAsync(token);
// Process message here
}
}
catch (WebSocketException)
{
throw;
}
}