Editors resigning because they published a low quality paper Very recently the chief editors of the journal 
'EMS SURVEYS IN MATHEMATICAL SCIENCES'
resigned because they published a paper (whose "methodology does not contradict Cantor’s and non-standard analysis views and is based on the
Euclid’s Common Notion no. 5 “The whole is greater than the part” " - from the abstract) which turned out to be of questionable quality.

Apparently the editors were "unaware of what was happening" (statement of the editorial board). This seems very peculiar to me; of course it happens here and there that an accepted article contains a minor error, sometimes even a major error. But usually the editors do not resign simply because they accepted a paper with flaws. Does anyone know of similar cases? In this particular case the paper will apparently not be retracted, even though apparently none of the editors was aware that this will be published. Why would editors choose to publish it nevertheless?

Officially (according to the publisher, as quoted here) "it seems that there is not enough grounds for a formal retraction." And yet the statement suggests that the editorial board is thoroughly unhappy.

Remark: I am particularly interested in mathematics journals (hence the tag). However, I am also interested in other fields.
It's decently common. I Googled for "peer review failure editor resign" and some examples are: 1, 2, 3, 4.

You ask "Why would editors choose to publish [the paper] nevertheless?" There're many possible reasons as to why editors may choose to publish a flawed paper:


Some members of the editorial board approved of the paper and still do, while others didn't (and the ones that didn't are the ones resigning). Journals typically do not get every member of the editorial board to approve a paper before it's accepted.
They made a mistake, but now that the paper is already published, they don't consider the errors critical enough to retract it (or they don't consider it fair to the author).
They realized the paper is dubious but decided to err on the side of acceptance. People who subscribe to this idea think, "referees only give opinions; the real peer review happens after a paper is published".
The journal is currently lacking papers, so they're inclining towards accepting more papers to fill their issues.
Difficulty communicating with the author, e.g. if the author isn't very responsive, then editors might choose to accept "as is" rather than wait several months for an author response (especially if the author isn't likely to make major changes to the manuscript). I also remember reading about a flawed paper that was accepted because the author was from the Soviet Union, and getting the author to correct it through the Soviet censors takes too much time.


In the case of this particular paper, the editorial board claims no knowledge of what was happening. At this point, it's speculation to try to figure out what actually happened. However, I would guess (based on my experience in publishing) that after the journal received the paper the desk editor attempted to find a member of the board to handle it, but everyone contacted either declined to handle it or simply did not respond to emails. In that case the desk editor can hardly let the paper sit there collecting dust, so (s)he did the next best thing which was to DIY, with less than ideal consequences. I've seen this happen and even done it myself quite a bit. I've never actually ended up in the news for doing this, which shows that usually DIY-ing doesn't lead to problems. But if it does, that's when we look at one another and sigh.