My Sony TRV9 camcorder started displaying this error message then shutting down when using a 4 year old LiON battery. I noted that the battery seemed to charge up, yielding an output voltage of 7.96. That seemed good, given that it was listed at 7.2 volts... Nevertheless, I replaced the battery with another new (aftermarket) one and the camera began operating fine, displaying no error message. THAT battery charged up to 8.42 volts...

Found the answer. A small yellow board needs to be changed. Not something I'm comfortable doing. Taking it to the camera shop... Rees