I had a working project, and made some customization and all of a sudden started getting the above error. I lost nearly a whole day troubleshooting this issue, rebaking the navmesh, redoing the agent settings, adding debug code, reading pages and pages of unity docs, as well as google results, etc. etc. Only to find out the error was 'expected'. I finally got lucky and found the solution in this thread here: https://forum.unity.com/threads/cas...nt-type-causes-failed-to-create-agent.485847/ The 'problem' was that I had added a new agent type. The procedure/interface was just like adding a new type for everything else (tags, layers, etc), so I never realized additional steps were required to make a new agent type work. Nothing in the documentation stated that the standard Navmesh is ONLY for the 'Humanoid' agent, and that adding a new type requires extra procedures. Could you modify the Navigation pages to mention this fact? Somewhere in the more general sections that people are more likely to see, and not buried somewhere preferably, 8^). Would possibly save a lot of people a lot of headache and lost time troubleshooting something that could be avoided with a quick mention in the documentation.