SD card failure.
After taking a few shots yesterday I tried to remove the SD card from my Canon SX50 but pushing down on the card did not release it and I had to use some force to yank it out of the slot. I was a bit shocked to find that the card was damaged. I was also worried that I might have also damaged the camera's internal connections but, fortunately, a replacement card slotted in and is working properly. The damaged card is one I have used for a few years in several cameras and I suppose the damage can be put down to "fair wear and tear". It's a pity the camera is working OK as I might have had an excuse to buy a new one but I am happy with SX50 so I have decided to keep it.