I recently got a new error on my 3D printer.

Error: !! STOP called because of BLTouch error - restart with M999

It turns out that the connector to my Z endstop was faulty. I was able to put a new JST connector on there and it worked again. Another possibility is a wiring issue at the connection between the BLTouch and the extension cable inside your loom.

I thought I had a bad BLTouch so I ordered another one. I was able to cancel the order before it shipped.