It is my understanding that Krzysztof Findeisen's comment explains why the
DM-28583 fix didn't work for Ian Sullivan, but that both of you are saying the exact same thing (and now I am, too):
calexps written using weekly w_2020_50 up until weekly w_2021_06 may not be readable with new code
But I now plan to modify the solution on
DM-28583 so it will fix reading the files written in that time period as well. But I'll do that on DM-28583, so we can still close this ticket.
(Maybe all of the confusion is whether Ian's "No, ..." was intended to negate the original ticket description or Krzysztof's reply - in any case, I hope we're all on the same page now.)