As explained by Tony Ulwick in What Customers Want, the term customer “needs” can be confusing. It’s best to separate what customers want into outcomes (their desired end-result, or the “what”) and solutions (your answer to their need, or the “how”). Keep your interview focused on their outcomes, not solutions. If they offer a solution, simply ask, “What would that do for you?” Poof: You’re back into outcome space where you want to be.
More in article, Discovery Interview Blunders that Frustrate Your Customers.