Migration and cross-posting seem to be popular topics on meta. There is also often a great deal of discussion in the comments of a migrated question about whether it was migrated correctly or most optimally. It's clearly a problem that has not yet been solved.

The problem

I have recently come across a few questions that don't fit neatly into any one particular SE site. Some questions require the expertise from two different sites to answer completely and correctly. By only receiving the input from one site, the question will result in a suboptimal answer.

This one for example was already migrated from StackOverflow to ServerFault but could easily have been migrated to Security.SE instead. Broadly speaking, the security guys will have more experience dealing with security incidents and are more likely to know about possible Apache exploits but the ServerFault guys will have more experience with the practical aspects of taking servers offline, keeping the services running and restoring from backups. (Ignoring for now that many users have accounts on both of these two sites.)

This one could easily fit on SuperUser or ServerFault. It's a question about a Mac on a Windows network. This one on Fitness.SE could easily be on Bicycles.SE and is almost identical to this one that already is on Bicycles.SE. In this question, a moderator suggested cross-posting as the best option.

A simple way to find these sorts of questions is to go to any SE site and search for the topic of a different SE site. (Security tends to be a common theme in questions in all SE sites.)

It becomes more obvious when a sub-group splits out of an existing group such as Security.SE and Crypto.SE or Unix.SE and Ubuntu.SE. There are plenty of questions both on here and on the various meta sites asking if old questions should be migrated now that a more specific site exists.

Existing solutions

Cross posting has the problem that you end up with two (or more) different sets of answers on different sites. The original asker has to maintain all of them and the various answerers don't get to read other answers. It is discouraged on SE.

Migrating a question has the problem that wherever the question ends up, the answers won't represent all areas of expertise. Although there is a trail left from the old site, if a question is only migrated once or not at all (e.g. The first question I mentioned never made it to Security.SE) then the question will never see that expertise.

The proposal

An option to post a question so that it was visible on two (or more) sites at once but so that answers and comments from any site would be visible on all sites. A solution like that would solve both the problems with cross-posting and migrating. This could possibly be called "breadcrumbs" because when you are asking a question on one site, you are also leaving trails on other relevant sites leading to the question. Moderators should be able to add breadcrumbs from any relevant site to any question.

An alternative without adding any new code to StackExchange is to encourage moderators to migrate a question whenever they think it might benefit from the expertise of another site, so leaving a large trail leading to a single question. This seems inefficient but better than missing out on the expertise required to answer the question.


I disagree. Allowing users to easily mark their questions so that they can be viewed on multiple SE sites will lead to new users spraying their question around in the hope of getting more attention for them. This in turn will lead to more work as mods or 10K users have to clean up. Don't believe me? Usenet is a prime example (who uses UseNet these days??!!!??) - people would cross post to as many groups as they thought was relevant, but frequently the inhabitants of those groups would think that it definitely wasn't relevant and should never have been posted to their group.

Basically, I believe that allowing this sort of thing will lead to more questions that are only tenuously (if at all) on topic in the target site.

I personally see nothing wrong with manually cross posting onto multiple sites, as long as the question is relevant on the target site, and they mention in each copy of the question the other place(s) it has been posted. I have done this once myself, I had a question about PowerShell (1, 2) which could be answered either on SO or SF, so I individually posted to both (not that the SF one got any answers). There is a cross over between some of the sites, but I think there are very few questions asked that could legitimately fit into more than one site. (Note that I am talking mainly about the programming/IT sites, not the myriad of others.)

If you give people a feature that is easily abused, that is what people will do with it: easily abuse it.

  • I certainly do believe you and I agree with you. I didn't mention it because my post was already getting too long but there would need to be controls associated with breadcrumbs. Maybe it would be for moderators only. The details of who could use it and when are a topic for another time. Would you be more in favour if it were a tool to augment migrating a question? – Ladadadada Nov 20 '11 at 2:01
  • My original thought for this came from a security question on ServerFault. Security is pretty much applicable to all the programming/IT sites and people regularly ask questions about security on those sites that don't get migrated because they are on topic. Security is also related to many of the other non-IT sites. If you want to ask a question about bike locks, should you ask it on bicycles.SE or security.SE or both? – Ladadadada Nov 20 '11 at 2:12
  • @Lada there already is a tool for migrating these questions. Users with enough rep to close questions have a list of 5 related sites they can select if they think a question os off topic, I'm not sure if the mods have the identical list or a larger one. – slugster Nov 20 '11 at 2:33

I'm not convinced. While for a particular phrasing of a given question this might be true, I don't see any reason that the question in, well, question, couldn't be broken up into two different questions and posted on the appropriate site. I'm not seeing the value in being able to source answers to the combined question than for any other two distinct but related questions.

  • The first question I used as an example is a double-barreled question and hence could be split into two separate questions but this is rare. Most people ask a single question in a post. The other three examples I used can't be split. The searches I linked to all contain multiple questions that can't be split. – Ladadadada Nov 20 '11 at 1:54

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