Yesterday I updated the firmware on my A7II to V2.0.
I then did some testing with various lenses, including several Canon lenses via a Metabones IV adapter with V.46 firmware.
Everything was working swimmingly.
Today, I was getting things ready for a job tomorrow and put a card in the A7II to format. The camera came on for a couple of seconds and then showed "Camera Error. Turn power off and then on." The error kept repeating.
Earlier today I submitted a Pro Support application. I called the number and got a nice guy on the phone. He asked for my member number, I didn't have one so he looked to see what the status was with the application and couldn't find out anything. He continued to help me anyway. Nothing he suggested had any affect.
I am now, impatiently waiting for him to call back after getting more information for upper level support.
Its anathema to go on a job without two camera bodies. Fortunately, I haven't been able to sell my Fuji kit yet so will have it available if this can't get resolved tonight.
In all the years I've been using digital cameras professionally, ranging from the first version Canon 5 D through the 5DIII and then Fuji XT-1s this is the first time that I've had a problem with a firmware update.