diff --git a/rails_admin.gemspec b/rails_admin.gemspec
index 6d0955cf71..f4810a817e 100644
--- a/rails_admin.gemspec
+++ b/rails_admin.gemspec
@@ -24,4 +24,12 @@ Gem::Specification.new do |spec|
   spec.required_rubygems_version = '>= 1.8.11'
   spec.summary = 'Admin for Rails'
   spec.version = RailsAdmin::Version
+  spec.post_install_message = '
+    ### Upgrading from 2.x.x to 3.x.x ###
+
+    Due to introduction of Webpack/Webpacker support, some additional dependencies and configuration will be needed.
+    Running `bin/rails g rails_admin:install` will suggest required changes, based on the current setup of your app.
+
+    For a complete list of changes, see https://github.com/railsadminteam/rails_admin/blob/master/CHANGELOG.md
+  '
 end