I am selling a house flip that is under contract for $275,000. The appraisal just came in at $250,000! There are ways we can challenge that appraisal but it is so frustrating to have this happen. People want to buy a house for $275,000, the appraiser uses comps that support a value of $275,000, and he values it at $250,000. That basically means if he doesn't change his value I have to sell the house for $250,000 or find new buyers. He had one comparable property that showed a value of $250,000 after he made his adjustments, and the rest were much higher up to $286,000 so he could have easily come in higher.
Here is a video I did on appraisals if you are not familiar with them.