Current macOS 10.13 High Sierra support summary: macOS 10.13 High Sierra upgrade recommendation: upgrade with care For macOS 10.13 support you have to upgrade your Unity Editor to one of these versions: - 5.5.5 patch 2 or later (install Visual Studio for Mac for script editing) - 5.6.4 patch 3 or later - 2017.1.2 patch 3 or later - 2017.2.0 patch 3 or later - 2017.3.0 or later These versions include multiple fixes for disappearing assets on APFS, Unity Editor and Monodevelop crashes. If you encounter more issues with Monodevelop on macOS 10.13 it's recommended to manually install Visual Studio for Mac and use it for script editing. Future Unity versions are expected to switch to it anyway. Patches for Unity Editor can be downloaded at usual place: https://unity3d.com/unity/qa/patch-releases There will be no Unity 5.4.x fixes for High Sierra, you have to either keep your machines on macOS 10.12 or upgrade your project to Unity 5.5.x and later. In general 5.4.x and older Unity versions might work with High Sierra on HFS+ disk, but it should be considered as last resort workaround if you have to use older Unity versions on new OS. Xcode 9 works fine with macOS 10.12.6, so if you are in late development stages of your game, it's still recommended to stay on macOS 10.12. Other known problems, but not related to OS upgrade: - Global cross platform Unity Editor outage while opening project. Workaround: disable networking while opening project. There will be blogpost on this issue. Should be fixed by now on our backend servers. Original post: We are aware of some issues with Unity and macOS 10.13 (High Sierra) beta 1 release. We recommend waiting before updating to this macOS version until we finish investigating reported issues, one of which being trouble with assets appearing in Project View. Check back here soon – we'll keep updating this post as we learn more. Update: we were able to track down missing Project View items issue as APFS and Unity editor interoperability problem. We are working on a fix, though meanwhile we recommend to not upgrade your main filesystem to APFS or at least keep Unity editor and your projects on HFS+ partition. Update2: we have updated our Mac VR build with APFS fix. You can get it there: http://beta.unity3d.com/download/f196ae3d2614/public_download.html. Fixes for other Unity versions will follow shortly. P.S. you don't need to upgrade to macOS 10.13 to try new Xcode or iOS 11. Just keep using 10.12. P.P.S. general advice while testing beta OS'es, please consider installing it to separate partition to not interrupt your everyday workflow.