If your car has experienced the recent deluge occurring in California, I would suspect moisture in the charge port socket, possibly due to micro-cracking of the plastic. There is a post describing the replacement and a Youtube video, I believe, showing how it is accomplished.I just got the "not able to charge" message last night on my 2014 Volt.
Anyway, when plugging in, the charge indicator light on the dash stays amber. Or, sometimes it turns green and begins charging but, after about a minute or so, switches back to amber. Or sometimes it flashes amber. Any time there is an amber light, there is an audible click, much like the one that I hear every time the car begins successfully charging. I can't tell if it's coming from the charger or the car. Any time the charge indicator lamp is amber, the DIC displays the cryptic message "not able to charge".
-I checked the charge port prongs on the vehicle: all are straight and free of corrosion.
-I tried my 240v wall charger and the 110v charger that came with the car: neither will charge the car. In fact, when I plugged in the 110, the ground fault protection immediately tripped on the wall outlet.
-I drove around the neighborhood for about half an hour but still had the same issue when trying to plug in after.
-Battery charges up to half and car runs fine in mountain mode.
-Orange "engine" light on DIC is illuminated.
Without knowing the codes, I'm guessing this is a charge port problem.
For the record, I had a "service high voltage charging system" code after a long mountain mode trip. Dealer applied TSB solution back in November 2022.
Taking it to a dealer soon; I will have to check under the hood for the sticker that will tell me if I am still under battery warranty or not: currently at about 103k miles and coming up on 10 years since manufacture date. Fingers crossed...
And yes, I have searched the forums and have an idea of what's going on. Wish me luck!