CalDav Certificate Error

Hello,
My CalDav connection in eMClient suddenly stopped working, with an exception error:
12:53:35 CalDavMail [CalDAV / CardDAV] MailClient.Accounts.ConnectionException: An error occurred while sending the request.

When looking at the full logs:
12:53:35 CalDavMail [CalDAV / CardDAV] MailClient.Accounts.ConnectionException: An error occurred while sending the request.
—> System.Net.Http.HttpRequestException: An error occurred while sending the request.
—> System.IO.IOException: The read operation failed, see inner exception.
—> System.Security.Authentication.AuthenticationException: The remote certificate was rejected by the provided RemoteCertificateValidationCallback.
at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception)
at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm)
at System.Net.Security.SslStream.ReplyOnReAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Byte[] buffer)
at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory1 buffer) --- End of inner exception stack trace --- at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory1 buffer)
at System.Net.Http.HttpConnection.FillAsync(Boolean async)
at System.Net.Http.HttpConnection.ReadNextResponseHeaderLineAsync(Boolean async, Boolean foldedHeadersAllowed)
at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
— End of inner exception stack trace —
at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.AuthenticationHelper.SendWithNtAuthAsync(HttpRequestMessage request, Uri authUri, Boolean async, ICredentials credentials, Boolean isProxyAuth, HttpConnection connection, HttpConnectionPool connectionPool, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.AuthenticationHelper.SendWithAuthAsync(HttpRequestMessage request, Uri authUri, Boolean async, ICredentials credentials, Boolean preAuthenticate, Boolean isProxyAuth, Boolean doRequestAuth, HttpConnectionPool pool, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.DecompressionHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at MailClient.Protocols.InteractionController.CerificationValidationMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at MailClient.Protocols.Common.HttpClientLoggingHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
— End of inner exception stack trace —
at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.FolderSynchronizer.UpdateOptions(Uri[] baseUris, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.FolderSynchronizer.Bootstrap(WorkerStatus status, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.CalDavGenericCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)

It seems eMClient is no longer able to verify the certificate:
The remote certificate was rejected by the provided RemoteCertificateValidationCallback

It is a self-signed certificate, but it is installed in the Trusted Root Certificate store in Windows. And it used to work seemlessly.

How can I fix this issue? Thanks for your help.

Peter

What OS are you using?

Hi Gary, I’m on Windows 11.

This is an issue with the beta version of Windows 11, so you will not be able to sync CalDAV.

Can you contact me directly on gary@emclient.com

I’m having the same issue here (windows 11 too), I would love to make it work because of using eM client + Nextcloud!!
I already sent you an email, Gary, but it is rejected.

Any help to fix it?

Thanks!

I commented on your other post. Can you contact me directly on gary@emclient.com

Hi guys,

I am having the same issue now with the final Windows 11 version. Any chance this gets fixed? I need my calendar to by in sync…

Thanks!

Bye

As a side note: I am using a Let’s Encrypt certificate, which should be globally accepted, still it does not work. Same certificate works when accessing the calendar via https in browser…

If you are using Windows 11, please upgrade to the latest version in the Release History.

Thanks @Gary, with the version 8.2.1659.0 it seems to work just fine!

Bye