When \externalfigure could not find the file it used to graciously place a rectangle kindly telling the user that the file has not been found.But now, however, it seems the default in this case is a crash. Very annoying in comparison with the earlier behaviour.
I might make a mistake, but the MWE is as simple as can be.
The filename is test.jpeg, then this runs ok:
\starttext
\externalfigure[test.jpeg][]
\stoptext
But this crashes, see the log:
\starttext
\externalfigure[test.jpg][]
\stoptext
yours sincerely
dr. Hans van der Meer