For me, it was the supply hose.
It was a safety supply hose, which is supposed to auto shut off the water if a break occured.
Somehow it got mixed up. I forget the sequence, but it involved.
I had to shut off the water, then run the dishwasher for a minute, then turn on the water, then turn on the dishwasher again.
During one of those actions, the thing reset.
This is a reminder I need to replace that with a non-safety one.