On startup: obsolete timestamp with cdr 1

[frankgerhardt]

When running org-timeblock for the first time I get to see 3 empty days and the message obsolete timestamp with cdr 1.
I even get this message if I remove all my org files. It has probably nothing to do with my files.

I set debug-on-error but I can't get any more detailled information.

What's wrong?

• emacs-version GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.37, cairo version 1.16.0)
  of 2023-05-14, modified by Debian
• org-version 9.5.5
• org-timeblock from melpa