Make sure you are using the latest VRCSDK
If you are upgrading from Unity 2018, follow the upgrade instructions https://docs.vrchat.com/v2021.3.2/docs/migrating-from-2018-lts-to-2019-lts pay special attention to step 2.5 MAKE A BACKUP OF YOUR PROJECT BEFORE UPGRADING IT TO 2019.4
- 0d6daed: Add support for sync mode none on UdonSharpBehaviours
- #110: Improve default create script location, contributed by @FairlySadPanda