Gerry Cohen If you're closing with a title company, it's certainly NOT a deal-breaker.
I just closed on a property today with this exact same issue. The individual I was purchasing it from thought they owned it because they had a quit claim deed in their name from 2014. The property belong to a deceased family member and was then inherited by the spouse, who signed the quit claim deed to my seller.
However, the legal description of the property was not included in the deed. Naturally, this came up when doing the title search but thankfully my title company handled everything - I didn't have to do a thing.
Similar to what @Levi-Shemtov mentioned, they needed to get a completed lack of probate affidavit, copy of the decedent's last will, and a recorded death certificate with the county. They also got in touch with the seller to have them sign another deed to legally transfer ownership.
I just waited until closing, signed on the dotted line, and handed over the cash. I did have to pay around 300 hundred bucks for all that but it was well worth it, no question about it!
I can say without question that this deal would not have gone through if I tried doing all that myself.