External factor changed, invalidating correct answer

Question

I asked the following question on WebApps SE:

Can I view Google+ check-ins on Google Maps?

With Google Latitude closing down next month, this invalidates the correct answer to the question.

Should I:

• Unmark the answer as correct and edit my question
• Open a new question stating "...without Google Latitude"

The first solution means the original answerer will lose 15 points, even though, at the time, they were correct.

The second solution means the original question will still be available to the public, when its no longer correct / helpful.

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I believe the first solution would be best, but I think the original answerer deserves reward for their help.

Even if I remove the "answer mark" the user could start getting negative votes:

"-1 Google Latitude is no longer exists"

Answer 1

Quite honestly, if the answer helped you and was correct at the time, and there isn't an alternative answer that is now more correct, I'd leave it be. We can't be perpetual janitors checking for any answers that are now obsolete because something outside of the site or our control has changed. As an example, what are we going to do with over 3,000 Google Reader questions? Wipe them clean off of the site? Forget about someone losing 15 measly rep, that could lead to people changing rep tax brackets.

In the SQL Server world, this kind of thing happens all the time. A mock question from 2009:

• Q: "What is the best way to do x?"
• A: "Well, since SQL Server doesn't support foo, the most efficient way is..."

Two versions later, and SQL Server now supports foo. Do we go back to a 4-year old question and change the accepted answer because there is a better answer now? Probably not, and it's actually a pretty dicey problem, since some readers who come across the question will have the latest version and some will still be using the same version with the same limitations.

I guess I would suggest adding a comment to the answer (or even suggesting an edit to the answer) with a disclaimer that Latitude is dead. This will give the answerer the first opportunity to maintain their accepted status by updating the answer with a new alternative (if one exists).

Answer 2

Generally it's a good thing to keep questions and answers up to date. So if circumstances change and now a different answer is the correct one, accepting that/unaccepting the obsolete one is justified.

The answerer will lose 15 points from that, but the reasons for the unaccept are clear and understandable. Making the internet a better place by keeping the information up to date should easily outweigh those 15 points.

To avoid that the answer attracts downvotes, the easiest way would be to edit in a disclaimer that explains the situation. If it states that the answer previously was useful but now became obsolete, then nobody will feel misled.

Answer 3

Here's an answer of mine (How to Style a Checkbox Using CSS) that fell into this category -- the widespread availability of CSS3 functionality meant that my original answer became invalid. Someone pointed this out in a comment. I left the original text but edited to add a new answer. Interestingly, I believe I ended up with more upvotes after the new answer than I got originally.

So I concur with Aaron that I would comment on the accepted answer, both to warn other readers and to give the poster a chance to update their answer. If they don't, I'd eventually un-accept their answer and modify the question.