I have the same issue.

I've found that not only was it Lighting but also Reflection Probe.

Again, doesn't actually break the game, but it's nice not to have all these errors.

It is a problem with the UVs, select the object on hierarchy and with Select, search for Generate Lightmapping UVs and check on this property. I resolve the problem by this way...

Put everything in the Hierarchy under an empty Game Object, then select Game Object, apply Static under Yes for children. Then uncheck it from Static and Yes, to apply to children. You can then remove everything from the GameObject and it removed the errors. For some reason in 2018 versions there is a a problem with Static features. I kept receiving this error (32 in fact) every time I) tested a scene and then exited. After using this work around the errors went away and have not returned.

This Error for me shows up whenever I set an Object Static. I thought this error was because of Occlusion, but even after removing Occlusion the only way I got rid of the Error.. was to remove Static from every object in my Scene, any Object seems to trigger this in my case.

I get about 30 of these any time I do anything that relates to any prefab (whether I search for one, select one, apply to one, etc.)
They don't cause any problems, they're just there.

I had this start after importing my Character from the Previous version.
The character is just the All Stars Character from the Asset store.
Removing the Character has not fixed the issue
and the error give no reason nor file that is causing it. Very frustrating