On Friday, United Airlines flight 59 from Frankfurt to San Francisco had to turn around when a toilet overflowed. The Boeing 777-300ER was at 30,000 feet around 70 nautical miles northwest of Amsterdam when pilots asked to enter a holding pattern to troubleshoot the lav. Half an hour later they turned back.
Apparently one of the lavatory toilets “overflowed” and what was called “the soup” spilled into the cabin, with an unbearable stench.