Unable to re-add US Holiday Calendar - SierraOS

I'm have same issue but with UK Holiday Calendar, the old work around was to go in System Preferences and click on Language & Region - make sure "Region" is set to your country and "Preferred Languages" has the primary set correctly at the top - yours should be English (US).

Saying that it doesn't seem to work for me, you might have better luck.

Yes, that's all correct - same for me but with English (UK) set as primary - when the issue occured in El Capitan the reason was identified as English being generic (i.e. not set to any country), looks like we will have to wait for an update to resolve.

Like others here I also see that the Apple tick box does not appear to work. In this sort of situation manually subscribing to the relevant shared calendar is the simplest solution.

Here is the UK one I use - https://p01-calendars.icloud.com/holidays/gb_en-gb.ics

Here is an alternative UK one - webcal://ical.mac.com/ical/UK32Holidays.ics

Here is a US one - webcal://files.apple.com/calendars/US32Holidays.ics

and here is a Monaco one which someone else asked me for and was hard to find - https://calendar.google.com/calendar/ical/fr.mc%23holiday%40group.v.calendar.goo gle.com/public/basic.ics

I'm facing the exactly same problem - only with Finnish Holidays (FI Holidays) since I'm Finnish. Hopefully Apple will come up with a fix!

I have recieved a bunch of error messages in my Console after this occurred, not sure if it's related to this problem somehow...

The latest Sierra update (10.12.4) appears to have resolved the Holiday calendar issue - on my system anyhow.

Thanks! This worked great.