[HalfEmptY]

I Will Post this again-
Liike others, Just entering the full ESN did not fix the error for me, so... I did this and it works.

I'm using NVIDIA Shield 2017, Netflix Addon 16.3 and Full Netflix ESN listed in Nvidia About Info

Android NVIDIA Shield users This will -temp fix the validation error

As I said, This worked for me.:
Important: make sure your full ESN appears in the Netflix addon settings, (because you are going to need that info to be listed in the settings.xml for this work around)

1.With a file explorer - Go into your
kodi/ userdata/addon_data/
And rename the folder (plugin.video.netflix) to something like (plugin.video.netflix1)

2 Restart Kodi and start the Netflix addon. Follow the directions for fist time use - enter your Email and Password ... Once the addon loads and you see your profiles Close Kodi.

3. With a file explorer- Go back into
kodi/userdata/addon_data/plugin.video.netflix.
You will see that some files are missing in there.

4. Go to your renamed Netflix folder (plugin.video.netflix1) and select SHOWS, (if you have shows in your Kodi Library). select DATABASE, MANIFEST.MPD, MANIFEST.JSON, MSL_DATA.JSON, LIBRARY.NDB2, and SETTINGS.XML. Copy those files to the new
plugin.video.netflix folder and restart Kodi.

Everything should be back working including 4K and Atmos.