The forums here seem to show a LOT of gearbox fault threads but not many recent so why not start a new one.

Drove the Jag about 50 miles today. For the first 45 miles with 3 stops for errands no problems at all. Then cresting a steep hill at very low speed with the steering cranked all the way to the right the engine raced up to maybe 4k RPM with no change in vehicle speed. I figured it was the odd uphill to the right angle maybe pushed the ATF to a weird position. 100 feet later at stop sign I hit the gas and car accelerates as always. Until about 40 MPH when suddenly engine jumps from 3k RPM to 5k RPM while the car is slowing down, clearly engine and transmission are no longer working together. At this point I am only 2 miles from home and manage to get there with the car seeming to randomly disengage the engine from the transmission every minute or so. As I pull into the driveway the dash shows an orange light and says "Gearbox Fault". No kidding. I try to park in my driveway and cannot, I can't get any forward gear. Drive, 2, 3, 4 sport mode, ...nothing works, the engine just spins without the car moving. Reverse works perfectly normal.

Go inside and stew for an hour then go back outside to the car. Car works normally and the gearbox fault light is out. Granted I wouldn't go beyond my driveway for fear of needing a tow home.

Reading old forum threads it seems like this could be a wet Transmission Control Module due to water from leaks under the windshield or blocked sunroof drain vents. Makes total sense, we had tropical storm Debby come by and dump a few inches of rain on the car over the last 36 hours. Could that be it? I am very hesitant to drive this car beyond the end of the street at this point.