1. Property appraisal is too low
2. Repairs required in the contract haven't been completed
3.Sellers say they can't make move out date
4. Buyers can't qualify for a large enough mortgage to buy the home
5. Buyers purchase a new car 2 weeks before closing
6. The inspector finds mold in the crawl space
Good agents have run in to these and more and know how to work around them. It is best to speak to buyers up front about possible issues before they happen. Make sure buyers are qualified, sellers are ready to move, the home is in good condition, and the home meets market comps plus any other areas of concern are met before listing the house and/or submitting an offer. Crisis prevention is our way of life.