Officeholidays ICS Calendar fails to import - One identified item in invalid format


most recent eMClient version 8, free license.

subscribing to ICS Calendars on Officeholidays always fails with an error:

1:46:43 Internet Calendars Web Calendar Synchronizing folder ‘/
11:46:43 Internet Calendars [Web Calendar] MailClient.Storage.Application.OperationException: Synchronizing folder ‘Internet Calendars/’ failed due to the following error: One of the identified items was in an invalid format.
—> System.FormatException: One of the identified items was in an invalid format.
at MailClient.VObject.CalendarReader.StringToDateTime(String value)
at MailClient.VObject.CalendarReader.LoadDateTimeValues(String encodedValue)
at MailClient.VObject.CalendarReader.LoadValues(ValueType type, Encoding encoding, Nullable1 separator) at MailClient.VObject.CalendarReader.LoadProperty(String line) at MailClient.VObject.CalendarReader.LoadFromReader(Calendar calendar) at MailClient.VObject.CalendarReader.LoadCalendar(Calendar calendar) at MailClient.VObject.Calendar..ctor(TextReader reader) at MailClient.Protocols.WebCal.WebCalCalendarSynchronizer.Synchronize(IItemSynchronizeContext1 synchronizeContext, Folder folder, CancellationToken cancellationToken)
at MailClient.Protocols.Common.ItemSynchronizer`2.<>c__DisplayClass37_1.b__6(WorkerStatus status, CancellationToken ct)
at MailClient.Protocols.WebCal.WebCalGenericCommand.Execute(WorkerStatus status)
— End of inner exception stack trace —

Could you please fix that, or at least give us a hint what to edit in .ics file so it would be parsed correctly with eMClient?

Monday 05 October 2020 :: 1250hrs (UTC +01:00)

Hi @aseg3

I have just successfully downloaded and installed from:
the file austria.ics
Unfortunately I don’t know the process that you went through.
Here is what I did:
WITH eMC in view (top left) Menu ->File ->Import ->iCalendar (.ics)
->Cut & Paste into top field ->
->In lower field ->Select folder ->Select Local Folders ->New Folder
->Enter name for new Folder ->Follow instructions

Personally I directly download *.ics files save them to my system and install
diectly from the calendar file, that way I always have a copy of the file,
if you choose to do this, instead importing from the site as above point
to the file you have downloaded.

¡Saludos desde la soleada España!


[email protected]


I’ve been trying out eM Client since this issue and it’s now a different kind. With Free License and Version 8, the initial adding of the Officeholidays .ics URL works, but later fails at synchronizing with error:

[Web Calendar]Synchronizing folder ‘Internet Calendars/Austria Holidays’ failed due to the following error: String ‘20210226T24607’ was not recognized as a valid DateTime.

Validating the .ics gives out warnings, but not errors:

So can you please fix this? It doesn’t seem like a huge thing to do, since the string looks in a reasonable format for a timestamp.

I know that the Austrian Holiday Calendar is an option to import, but i’d need a Slovenian calendar too (

Also deleting internet calendars is hard, since mostly you get an error that the “account is read-only”.

To delete an Internet Calendar, right-click on the calendar and choose Delete.