I saved up and bought a D810. took a ton of photos and went to import my photos into LR3.6. The files were .NEF format. I have been trying to figure out what I need to do, buy, which deity to sacrifice a animal to, in order to make this beautiful machine work. Adobe live chat did nothing.
The D60 was first supported in Lightroom 1.4.1
The D700 was first supported in Lightroom 2.1
The D5100 was first supported in Lightroom 3.4.1.
The D810 was first supported in Lightroom 5.6.
So to edit Raw D810 files you need to upgrade to 5.6.
Alternatively, you can download the free Adobe DNG Converter, convert all D810 Raw files to DNG format then edit the DNGs in LR 3.6.