This issue is occurring in Unity 2021.2.10f1 I'm generating procedural meshes, storing those meshes in Scriptable Objects, and then assigning them to a mesh collider. However, upon upgrading from 2020 -> 2021, I started getting these errors where I assign the Mesh Collider: Code (CSharp): This Mesh Collider is attached to GameObject at path 'Prefab Mode in Context/Walkway_Small_Corner' with Mesh 'Walkway_Small_Corner_mesh_fc3f22ce-e547-470e-ab87-5ceb032bd183_0' in Scene 'Walkway_Small_Corner' but doesn't have Read/Write enabled. Only colliders that have default cooking options, are not scaled non-uniformly, and their meshes are not marked dirty can leave this disabled. The stacktrace comes back to something as simple as: Code (CSharp): submesh.MeshCollider.sharedMesh = unityMesh; Why would this error be occurring? How can I set the read/write flag of a mesh? I can't find anything about that anywhere. The mesh collider is definitely (1,1,1) scale, I am quite sure the cooking options are default, but I guess their meshes could be dirty as they are being updated in the editor and baked procedurally.