As some of you may have noticed, Facebook does not allow advertisers to ask for users' gender preferences anymore (the "Interested In" field in Advanced Options). They started last year, removing the possibility for European countries, while now they're extending it to everyone.
This means that if you had used anything else other than "all" in the interested in section at Step 3 of campaign creation, your campaign failed and you have come across this screen:
What next? You should click on "Edit Campaign" and re-open the campaign that could not be published, and click on proceed until you get to the third step.
From there, make sure that the "Interested in" section looks similar to this:
(Relationship status can be specified, just not "Interested in", which needs to remain set to "All".)
You also will need to confirm at the pop-up between step 3 and step 4 that you are not running a test on "Interested In".
This is what the pop-up will look like without Interested In selected for a split test:
Here is what it looks like if you do have "Interested In" selected for a split test, and this should be avoided and will result in your campaign failing.
Once you have fixed your campaign settings, you can proceed to publish your campaign successfully!