So, someone posts a question that is bad - it doesn't contain all of the information needed to really answer the question. Fortunately, it's pretty easily fixable by adding more information.
In this example, people asked for clarification (the full error message), which reveals that the problem is in code the user hasn't given us. Fair enough, we then ask for the missing code.
At this point, someone posts an answer which guesses at the problem, while I understand the want to answer quickly and the logic of guessing the issue, I feel this kind of answer really isn't useful, as it could be wrong and it could mean the question just gets left in that half-asked state.
I would argue the better course of action is to get the asker to clarify until the question can be answered with more certainty.
These kind of answers tend to, however, get upvoted pretty fast, so I'm not sure whether that just means that I'm wrong and that's just the way the questions should be handled, or whether there is an action I should take (downvoting the answer? I would already downvote the question until it was fixed).
So, to clarify the question at hand, should I be downvoting answers that guess at a (very) unclear question?