If you have installed the Keystone.js, and properly installed mongodb, but when tried to start the keystone thought command node keystone.js, you might get the error

{ [Error: Cannot find module ‘../build/Release/bson‘] code: ‘MODULE_NOT_FOUND‘ }   js-bson: Failed to load c++ bson extension, using pure JS version

Once you have this problem, you could open the package.json inside node_modules/keystone/package.json, then change the line of mongoose to version 4.4, reinstall the moongose, it should be okay then.

Keystone, Start, Failed to Load Bson