Bug Do not use ReadObjectThreaded on scene objects!

Hi there!

We've upgraded Unity versions from 2019.2.21 to the current 2020 LTS version (2020.3.21f1) and found a new error pops up 30-40 times when we hit play:

Do not use ReadObjectThreaded on scene objects!

It can't be clicked into to find the offending script and prevents us from building, but not playing. I did a search for the error and found only a few sparse results. These were either irrelevant or didn't solve the problem. We performed solution-wide searches for functions like LoadAllAssetsAtPath and GetMainAssetTypeAtPath and returned no calls, even within third party packages we are using in our project.

One potential lead is a warning that we get upon opening our project. For 3 of our trees, we'll get an error like:

The tree Tree-Spruce couldn't be instanced because the prefab contains no valid mesh renderer.

However, we don't use trees in the terrain system at all, and child objects on each tree prefab contain valid sprite renderers (Camp Canyonwood utilizes sprites in 3D space). Does anyone have any ideas for where we might find the problem? We'd really rather not be forced to get this answered by Unity themselves for the low-low price of... let me see here... $2,200.00 per seat, per year.

 

Sorry for the self-bump, but we would really really appreciate a reply from Unity on this if possible. We now have an issue with crashes brought about by some alleged Unity bug when we utilize threaded A* in the Aron Granberg A* Pathfinding Project package. He suspects that we need to upgrade out Unity version, but these errors are preventing us from doing so.