I am new to Emacs and Org mode. I am using Emacs for Mac version 27.1-1 on Mac OS Version 11.2 Beta.
When I try to insert a timestamp using C-c . or M-x time-stamp, Emacs shows error message Invalid version syntax: '' (must start with a number) in the echo area.
How can I debug this, to be able to insert a timestamp?
Same problem here: Updating from org 9.3.1 to 9.4.4 (Emacs 26.3 on Ubuntu 20.04 LTS) and suddenly C-c . and its derivatives C-u C-c ., C-c !, and C-u C-c ! returns the Invalid version syntax: '' (must start with a number).
The keys are still correctly bound though: C-h f org-time-stamp tells me so.
Inspired by kevzettler's answer I moved the new install out of my dot-emacs elpa dir and this resolved the issue, at the price of being back to version 9.3.1: ~/.emacs.d/elpa$ mv org-9.4.4/ ../. So, something in org 9.4.4 causes this.
Solution: update to version 9.4.4-8-g33de2b-elpa --- listed as 20210111 in Emacs package manager.
