EDIT: So I realized that my Fiji was in fact not up to date.. I ran the updater again this morning and everything is back to normal.
Why the updates were not applied the other day, I have no idea, nor do I understand why it stopped working sans any update.. But it works now, so all is well.
I will piggyback on this thread because I ran into the same problem as you included in the first post @m-entrup (see SS below).
I have been using the script editor (jython) for over a year and this problem has never occured untill now, following a Fiji update. Suddenly none of my scripts will run, all resulting in the same error as in the included pic. I couldn't say for sure which update caused the problem, as I had not run the updater for ~2 months untill yesterday evening, but see the bottom screencap for my current version info. If you need more info let me know and I will reply promptly.
Does anyone have a clue what went wrong? Can I fix it? I did some googling, and I found this discussion on GitHub, but I am more biologist than programmer. If someone could offer some advice, I would appreciate it.
The error could be on my end as well, I have not made any changes other than updating Fiji, but this is a networked university desktop, subject to updates from IT.
PS. pasting code to the jython interpreter still works.
(Windows 7 Enterprise)