Lazy<T> error

Library/PackageCache/com.unity.xr.management@3.2.13/Editor/Metadata/KnownPackages.cs(34,24): error CS0433: The type ‘Lazy’ exists in both ‘System.Threading, Version=1.0.2856.102, Culture=neutral, PublicKeyToken=31bf3856ad364e35’ and ‘mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’

Anyone run into this before? How to fix?

The error appears when I import the ARKit XR Plugin.

Does this happen in a clean, new project? What version of Unity are you using? What other assets or packages do you have installed (Maybe change Unity Registry to In Project in the Pack Man UI and paste another screen shot)?

For context, I tried adding AR Foundation and AR Kit XR Plugin (same versions as above) to a new project in Unity 2019.4.10f1 and I don’t see this error.

Unity Version: 2019.4.10f1.
It does not happen in an empty project.

Here’s the screenshot with “In Project” selected.

Here’s mine and I get no errors. Other than version differences (seems some of the packages you have installed currently are older) the only thing different is the Build Report Inspector, which doesn’t seem to be a current Unity provided package and not in the set I can install by default.

At this point it’s either that package or it’s something in your project itself. I would suggest starting from a clean, new project with all the packages here installed then start adding stuff back in till you get to the break.

i Know this was a couple months ago but im using 2019.3.15 , my project was perfectly fine making a VR game then i decided to give Bolt a try and now i cant get rid of this damn error. I have no idea but it seems like theres multiple scripts using the same Lazy I know bolt came out in July so i thought it might be possible it could be indirectly connected to what were experiencing. Im like Noobin to the max over here so i dunno but i wanted to share that it happened for me immediately after installing Bolt

Turns out I had a DLL imported into my Assets folder called “System.Threading”. Deleting it resolved the issue.