Setting up an Nextcloud Caldav account gives a strange error about invalid URL

I am struggeling to set up a Nextcloud caldav/carddav account using an URL like this:

It works! Calendar an address book are syncronized.

However, I am keep on getting an error about an invalid URL:

21:49:59 [CalDAV / CardDAV]  Synchronisiere Elemente: Für Ordner
21:50:00 [CalDAV / CardDAV]  MailClient.Accounts.ConnectionException: Es wurde eine ungültige URL angegeben.
21:50:00    bei MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.ContactItemSynchronizer.CreateItem(Folder folder, Component componentPayload, Uri uri, String eTag, CancellationToken cancellationToken)
21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.CreateCardDavItem(Stream payloadStream, Uri uri, String eTag)
21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.CreateCardDavItem(ResponseItem item, Uri responseUri)
21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.DownloadItemsMultiget(IList1 uris, Boolean calDav) 21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.ProcessItems(Dictionary2 items, Boolean deltaSyncReport)
21:50:00    bei MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.Execute(WorkerStatus status)
21:50:00    bei MailClient.Commands.Command.Process(WorkerStatus status)

What is wrong?

Hello Frank,

If the account synces correctly, then I assume it’s just a bad communication between the server and eM Client. If you’d like to get rid of the error pop-ups, you can disable them in Menu > Tools > Settings > General > Operations window.