Database migrate fails in "stable" version

[RGJ (Richard - Communiteq)]

Nope. You’ll have to wait for Discourse 3.0 stable in January (or switch your forum to beta or tests-passed for the time being)

@sam

discourse-gamification is a very new plugin, we do not expect to support it on the stable version of discourse. The first officially supported stable version will be on the next release of Discourse