Fixing pink (shader/material) problems

If there is a mismatch between the Unity version that the WebXR package was created for and the version of Unity you are using, there may be an issue with some of the materials in the project. The result is a shader error and objects that look pink in Unity. Sometimes, this can be fixed by reimporting all assets (menu: Assets | Reimport). Otherwise, you can fix the issue by selecting each Material in the Project window (usually in a folder named Materials) and choosing an appropriate shader – in most cases, the Standard shader is fine for fixing this issue.