CS5 & ACR updates [Branched from Updating Adobe CS5]
I also have this issue, CS5 will not accept the Camera Raw update. I recently upgraded my Canon 7D camera to a Canon 5D Mark IV. I have read I may have to open my raw files in the Canon Camera DPP software first, save as a TIFF, then transfer to PhotoShop. Not what I really want to do but so far, haven't found a solution. Seems since Adobe went "Subscription Mode" on us, we're left in the dust... :o/