I want to render a 21960 x 3720 animation to png or jpg images. Yet when I click ok in the Render Animation dialog, I get a message saying:

Could not render animation:
Mpeg4 (.mp4) requires width and height to be even numbers. Please resize or crop the image before exporting.

Is my canvas just too big?
Is there any workaround?

Which version of Krita are you using? Make sure you use the Image Sequence tab, that way it won't bother you with complaints from mp4. Also if you want 21960x3720, then make sure the export size is also the same - mp4 complained about odd numbers and I don't see odd numbers in your canvas size.

My version is 4.2.5
I already was in the Image Sequence tab
Where do I find the export size ?

I understand a little better what's going on and made a bug report:
https://bugs.kde.org/show_bug.cgi?id=412599