Oh, I just see that 99of9 already reported T394626 - I guess these two are intermingled.

Ah, I merged it in the wrong direction.

As 99of9 reports on the merged task, the problem seems to be that https://www.wikifunctions.org/view/en/Z24330 used to work, but doesn't anymore, although all participating functions seem to work, and there is no apparent reason for them not to work anymore.

I have tested it on May 18, then connected the function as a display function, and later that day it stopped working.

I'm also seeing "unspecified error" appearing in other places. For example, https://www.wikifunctions.org/view/en/Z13894 used to work, but since I added one new test, it fails most of the old tests as well.

These now seem to be working again.