AN UPDATE: On the PC on to which I want to import the third calendar, I created a calendar using the same name and colour. Then as a test, I created an event in it for today. When I tried to export the temporary calendar, nothing happens. How coincidental (read odd) is that?

several things, but first of all what are you calling it. I often see folk using file system characters in object names that then turn to a mess when the object is supposed to be turned into a file. Things like /\%$and : for example.

I am not sure what you are talking about? What am I calling what? I am talking about one of my calendars will not export, not object names or text files or whatever. I have three calendars, call them A, B and C. A & B will export as files like A.ics, B.ics but C does absolutely nothing. I am not sure what your comment about [Things like: /\%$and : for example] mean. I cannot see any connection to exporting calendars. When they export they use the calendar name plus the extension ICS. Please explain, thanks. You lost me, along the way.

I am not sure what you are talking about? What am I calling what?

What are you calling the problem calendar. The actual name you are using. not some placeholder. At this point I am guessing that is what the problem is.

It has a simple name Health. No non-alphabet characters, hieroglyphics, place holders, punctuation marks or whatever. My three calendars on all three of my Tbird installs are:

My Calendar PCCH Health

The third one Health will not export on any of my TBird installs. How strange is that? Is it the name, something unique to the calendar, three is too many calendars, or some other oddity? I cannot see TBird limiting calendar export to only two? I'll add a few more test calendars to the first install and see if they will export.

Chew on this. I created a TEST calendar on the PC I want to export from to test the export feature. I tried EXPORT and it created a TEST.ICS file in a shared folder. On the second machine I opened TBird and using "Events and Tasks" I imported it into the TBird install. The "TEST" calendar was fine and it opened normally. So this begs the question why does my HEALTH calendar not export from any of the installs? I need to dig deeper.

Open the error console (ctrl_shift+J) Make sure Thunderbird is active in the foreground. I keep doing it with Firefox in the foreground and it just makes a mess of the page I was on. Clear the error console using the trash icon on it's toolbar. Try and export your troublesome calendar.

What appears in the error console. (right click in the error console and select copy all messages and paste into your reply.)

Thanks for the suggestion, but I solved it. You will never guess why it happened. I could not find the cause anywhere in FAQs, help files etc. Many of the files are out of date. Perhaps when posting a question, people could specify the release number, operating system type and release etc. Then the questions could be grouped logically, that would save a lot of time and frustration. This is just a suggestion, it is not a criticism. I know you are mostly volunteers.

So what is the solution? I have the same problem Cheers

Sorry but that was 6 months ago and I don't remember what I did, and I cannot find my notes either. All I remember was it was a simple fix. If I ever find my notes I'll post here.