Connection failed on Nextcloud CardDAV CalDAV - : Invalid character in the given encoding. Line 932, position 258

Hi, I’ve been trying to communicate on email for this issue for some time, but have yet to find a resolution. I have been given the URL to your “Online support center” over email, but can’t file a report as I am not a pro user: “Please login to our Online support center here and submit a ticket so one of my colleagues from tech support team can assist you.”

I can’t properly sync my Nextcloud instance with eM Client, it starts syncing after initial setup then, the error I am given in the software is: “Connection failed”.

The log is below (private and potentially private info redacated or changed as this is a public forum).

OK</d:status></d:propstat></d:response><d:response><d:href>/remote.php/dav/calendars/user/user@nextcloud.com%20(Google%20Calendar%20import)/REDACTED</d:href><d:propstat><d:prop><d:getetag>REDACTED</d:getetag>cal:calendar-dataBEGIN:VCALENDAR
VERSION:2.0
PRODID:NextCloud Calendar
BEGIN:VEVENT
UID:REDACTED;
SUMMARY:REDACTED
SEQUENCE:0
LOCATION:REDACTED
DESCRIPTION:REDACTED
STATUS:CONFIRMED
CREATED:20201027T093917Z
LAST-MODIFIED:20201027T094014Z
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER;RELATED=START:-PT15M
END:VALARM
DTSTART;VALUE=DATE-TIME:20190731T090000Z
DTEND;VALUE=DATE-TIME:20190731T095000Z
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR</cal:calendar-data></d:prop><d:status>HTTP/1.1 200 OK</d:status></d:propstat></d:response></d:multistatus>

12:12:13.486|064|
12:12:13.486|064| Exception: MailClient.Accounts.ConnectionException: Invalid character in the given encoding. Line 932, position 258.
12:12:13.487|05A| —> System.Xml.XmlException: Invalid character in the given encoding. Line 932, position 258.
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.Throw(Exception e)
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.InvalidCharRecovery(Int32& bytesCount, Int32& charsCount)
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.GetChars(Int32 maxCharsCount)
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.ReadData()
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.ParseText(Int32& startPos, Int32& endPos, Int32& outOrChars)
12:12:13.487|05A| at System.Xml.XmlTextReaderImpl.FinishPartialValue()
12:12:13.488|05A| at System.Xml.XmlTextReaderImpl.get_Value()
12:12:13.488|05A| at System.Xml.XmlReader.InternalReadContentAsString()
12:12:13.488|05A| at System.Xml.XmlReader.ReadContentAsString()
12:12:13.488|05A| at System.Xml.XmlSubtreeReader.ReadContentAsString()
12:12:13.488|05A| at System.Xml.XmlReader.ReadElementContentAsString()
12:12:13.488|05A| at MailClient.Protocols.CalDav.ProtocolCommands.ResponseItem…ctor(XmlReader responseReader)
12:12:13.488|05A| at MailClient.Protocols.CalDav.ProtocolCommands.MultiStatusResponse…ctor(HttpResponseMessage response, CancellationToken cancellationToken)
12:12:13.488|05A| at MailClient.Protocols.CalDav.ProtocolCommands.ReportCommand.CreateResponse(HttpResponseMessage response, CancellationToken cancellationToken)
12:12:13.488|05A| at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
12:12:13.488|05A| — End of inner exception stack trace —
12:12:13.488|05A| at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
12:12:13.488|05A| at MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.DownloadItemsMultiget(IList1 uris, Boolean calDav) 12:12:13.488|05A| at MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.DownloadCalDavItems(IList1 uris)
12:12:13.488|05A| at MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.g__AddOrDownloadItems|14_0(DownloadItemType type, Uri uri, Action1 downloadAction, <>c__DisplayClass14_0& ) 12:12:13.488|05A| at MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.ProcessItems(Dictionary2 items, Boolean deltaSyncReport)
12:12:13.488|05A| at MailClient.Protocols.CalDav.Synchronizer.SynchronizeItemsCommand.Execute(WorkerStatus status)
12:12:13.488|05A| at MailClient.Commands.Command.Process(WorkerStatus status)
12:12:13.488|05A| — End of stack trace from previous location —
12:12:13.488|05A| at MailClient.Protocols.CalDav.CalDavAccount.<>c__DisplayClass40_1.<b__2>d.MoveNext()
12:12:13.488|05A| — End of stack trace from previous location —
12:12:13.488|05A| at MailClient.Protocols.CalDav.CalDavAccount.<>c__DisplayClass40_1.<b__2>d.MoveNext()
12:12:13.488|03B| AccountBase.ChangeOnlineState : State changed to OFFLINE due BrokenConnection