Is it possible to know the list of removed users?

Today morning I learned that I have +4 reputation with notification "User was removed". I calculated that probably this removed user posted me two downvotes. Simultaneously my (not very pleasant) discussion with some anonymous user (who had more than 1000 of reputation) also has disappeared. I suspect that exactly this user was removed, but unfortunately I forgot his/her name (which was just some numbers after "user"), so cannot check his/her profile (to look if he/she still exists).

So, I have a question: is it possible to know the list of removed users and the reasons why they were removed and also who removed them? I understand that this is rather very delicate question, so I admit that the answer will be absent or very diplomatic :)

• Just as a remark to the recent case I'll mention that you can see "user was removed" on many users' reputation tabs with a similar timestamp as here on MathOverflow. So it's possible that the same user was deleted on both sites today. Feb 25 '18 at 18:50
• Since it is a bit hidden in the long answer below, I will mention also in a comment that from Glorfindel I have learned about a way to find which posts were influenced by this: How can I find posts related to lost reputation due to a “user was removed” message? and Is it possible to know which posts were affected by user removal? (Of course, this is different from the main question here - which is to find the users who were removed.) Jul 10 '20 at 6:40

I'll also add that trying to find out who cast downvotes on my post is, in my opinion, not a constructive use of my time. But maybe some of the stuff mentioned below can be useful in some situations even when looking for useful information.

The third thing I should mention is that one of the key features of Stack Exchange software is that voting is anonymous. (And this is unlikely to change.) Although in some situations you might guess who downvoted/upvoted your post, you cannot know for sure. (To mention specific example to show what I mean, when I look at the OP's profile here on meta, I see how many upvotes/downvotes he cast on meta until now. And if later today this answer is at $$-1$$ and I see that counter showing number of downvotes on his profile page has increased, then it's quite natural to suspect that the downvoter might have been him, but it is very far from a proof.)

After the disclaimer above, let us have a look at your question, which can be interpreted in several ways.

1. If my reputation tab shows a change of reputation saying user was removed, is it possible to find out which user was it? No, if user's account is deleted and in situations where this leads to removal of votes, you cannot find out which specific account was removed. This is discussed in more detail here: Is there a way to know which user was removed?

2. Is it possible to find a list of all users that were deleted recently/during this week/during some specific time period? As far as I know, the site does not offer you possibility to do this. But you could use the data from data explorer and the fact that they are only updated once a week. (Currently it is Sunday morning around 3:00 UTC - it used to be on Mondays.) This means that some stuff which was deleted can still be in the database until the next update. (I think it might be reasonable to add additional restrictions so that you do not have too many results - there is a limit on number of results of SEDE query; SEDE returns only first 50000 results if the query returns more results than that. In this case, you say that users' reputation was above 1000, so you could use this query. Or you can try to restrict your attention on users above certain number of votes.) You can download the results - and then simply sit and wait, download results of the same queries during the next week - after the update of the data in SEDE - and compare them. You will get list of the users that were deleted.

4. I had exchange in comments with some user, now the comments are deleted. Can I find username/user account? We will have a closer look at this problem below.

How to find a user I interacted with - if the comments were deleted?

This is actually the part question which I can consider useful. It is possible that you had interaction with some user and you want to find that user - you have something to add. But the comments were, for some reason, deleted.

It definitely helps if you remember under which post you had the comment exchange.

Some things that can be tried are:

1. Check your global inbox. Sometimes, but not always, deleted comments stay there.
2. Long exchanges in comments can be moved to chat (automatically or by moderators). If the comment exchange you're looking for was rather long, it might be worth looking in chat. You can have look at rooms imported from main site. (Those are the rooms with the title "Discussion between userA and userB" and description started "Imported from a comment discussion on ...") Or you can look at your chat profile and check the recent messages posted by you. (If a conversation you were part of was moved to chat, the comments you posted in that conversation will also appear as chat messages in that room.)
3. If you remember on which question you had the discussion, you can check whether the comments can be found using Wayback Machine or whether they are still in Google Cache.
4. And you can also try to use data explorer - assuming that the deleted comments were already there before the last data dump, but the data in data explorer have not been updated since the deletion. (You can look for comments on specific post or for all comments under your post, etc.)

Of course, in neither of the above solutions you can be sure that you actually find the deleted comments. But if you are really looking for something, they might be worth trying. I will add link to this discussion on another meta: Are there some possibilities for users below 10k to see deleted posts of other users? In an answer to this question you can find a SEDE query which shows comments on a specific posts: Why were the constructive comments deleted along with one poor comment? If you would like to make a query looking for all comments on your posts, you can try to modify some of the queries here: Is it possible to search for posts/questions of an user $$X$$ commented on/answered by the user $$Y$$?

I should add that I can see that some users might see investigating stuff like this problematic. If a user decided to remove their account, it's basically their personal business. (And if it was done by moderators, then the reasons should be kept private, too.)

On the other hand, I also understand the natural curiosity - many users saw a recent reputation change citing "user was removed" on their profile page, so they might be curious what actually happened. (Although it seems that quite often - unlike in the case of the OP - the reputation change is negative, which suggests that in those cases upvotes were removed after the deletion of a user's account.)

In my answer I described some tools how to get an information about some deleted stuff - but all of this information comes from publicly available sources. So I hope that the answer I posted is acceptable even for users who have dim view on looking at accounts' deletions by regular users.

• Wow! So extensive answer to my "innocent" question. Many thanks for your time. I have already looked at users with more-or-less the name I vaguely remember and probably that user disappeared. I should tell this story to my good collegue Alex Ravsky (math.stackexchange.com/users/71850/alex-ravsky) who had high reputation on SE but had closed his account as a protest against two unexplained downvotes to his innocent question on meta-SE. So, the (virtual) life is rich of many such strange stories. Feb 25 '18 at 9:32
• It seems to me a bit premature to accept an answer so quickly. (Especially since we do not know whether it really works. I will try once again after the next update of the data in SEDE, but so far I did not find any 1000+ users that were removed.) Another thing is that if there is already an accepted answer, it slightly discourages others from answering - maybe somebody can offer much better answer for your inquiry. Mar 4 '18 at 9:07