I was doing a Santa photo shoot yesterday for a local store with my D90. I knew that I was going to be going through batteries during the shoot so I used my vertical grip for the extra battery power. I was also using a 16Gb sd card in the camera. At one point the battery indicator started flashing on the top lcd panel on the camera. So I switched batteries and was ready to go again. As soon as I closed the battery cover on the grip and turned the camera back on, the top lcd panel started flashing "Err". I tried turning off the camera and waiting a few seconds before turning it back on, I tried removing the lens and putting it back on the camera as well. Still that Err message was there and the camera wouldn't function. I had changed nothing but the batteries and this caused the Err message to pop up. So I decided to switch memory cards and suddenly the Err message disappeared and the camera was ready to go again. So I figured that the memory card was full and that was what had caused the Err message to appear. However when I returned home and checked the 16Gb memory card I noticed that there was only 45Mb used. Any idea what might have caused the Err message?
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