When I try to mark a question as a duplicate, I get a message that the URL is not valid. What's going wrong?
I did have trouble until I learned that the URL need to be the one that already has an answer. You need to mark the duplicate using the URL of one with an answer. If no duplicate has an answer, it seems to be impossible to "Mark as Duplicate".
Kevin, that happens because you don't have the proper URL for the question you want merged...here's what I mean.
Like Jim said, you have to hit the "mark as duplicate" option on the question that doesn't have an answer. This means that you need to take the URL from the answered question and post in the "mark as duplicate" field of the unanswered question.
However, I've noticed that URLs that end in #number will get rejected - just like you show in your print screen.
In your case, the question ends in #143667 , which is what I think messes up the URL.
Here's the method I use. You need to get the URL from the SEARCH RESULTS PAGE, which will end in
?source=search, instead of in #number, and use it like that in the "mark as duplicate" field.
This works every time for me.
So, let's say you have an unanswered question, A, which is a duplicate of an answered question, B.
Take some key words from the title of B and use them in the search bar located under your profile name (top right corner).
Click on the link shown in the search results page, and then take that URL, the one that ends in ?source=search, and use it in the "mark as duplicate" field of question A.
And boom, the two questions are now merged.