Unsupported Form builder or framework: active_admin - uninitialized constant ActiveAdmin::Inputs::DatepickerInput (NotImplementedError) about ui_datepicker-rails3

[kristianmandrup]

Sounds like the constant is referenced before the source file defining that module is loaded. The gem should load the source file only when you explicitly tell it to. See the configuration instructions. Should be easy to debug if you look into the code.

[kristianmandrup]

You can also look into the specs ;) the specs should demonstrate how to configure and ensure the constants are loaded and defined.