Unable to get Calendar to write a "Calendar Archive file to my desktop,

Hi Lee,

welcome to the Apple (user-to-user) Community,

re: Might someone Have a hint on what might be wrong?

Thank you for posting your question to the Community, and for thoughtfully sharing which Mac model, and iOS version that you are using, and what you have done (👍) to troubleshoot.

Am no expert I this area, yet your question surely deserves a response.

Wondering which Calendar you "host" on iCloud, (Mac iCal or ?)

and

if the export was from iCloud,

or

from the iCal Calendar on your Mac:

To see Apple's methods:

For the latter:

Apple Support have an article online:

How to: Import or export calendars on Mac – Apple Support

Above article comes from:

Calendar User Guide for Mac – Apple Support

______________________________________________

To Archive or make copies of the information you're storing in iCloud – Apple Support

says:

Re: Download a calendar from iCloud.com

1. 1. Sign in to iCloud.com with your Apple ID and open Calendar.
   2. Publicly share the calendar.
   3. Copy the URL of the shared calendar and paste it into the address field in your browser. Don't click Enter or Return.
   4. Change "webcal" to "http" and click Enter or Return. An ICS file will be downloaded to your default download location.
   5. Add the calendar to a calendar client, such as Calendar on Mac or Outlook on a Windows computer.
   6. Stop sharing the calendar.

iCloud Calendar keeps information from the last six months, and up to three years in the future.

Hope there's something helpful to you here,

and that you have more success following one of Apple's methods.

All the best :-)