The first user interview question should be about the last attempt

Ask someone whether they want your idea and you will get a polite forecast. Ask them to walk through the last time they tried to solve the problem and you get evidence: the trigger, the workaround, the cost, where it failed, and whether the problem was painful enough to revisit.

Specific past behavior beats imaginary future enthusiasm. It also makes the awkward answer useful when they did nothing at all.

What question reliably pulls your interviews out of opinion mode?