Fix Compare page throws 500 error when any branch/reference is not selected

app/controllers/projects/compare_controller.rb

@@ -25,9 +25,14 @@ class Projects::CompareController < Projects::ApplicationController
   end
 
   def create
+    if params[:from].blank? || params[:to].blank?
+      flash[:alert] = "You must select from & to branches"
+      redirect_to namespace_project_compare_index_path
+    else
       redirect_to namespace_project_compare_path(@project.namespace, @project,
                                                params[:from], params[:to])
     end
+  end
 
   private
 

changelogs/unreleased/i--25814-500-error.yml

+---
+title: Fix Compare page throws 500 error when any branch/reference is not selected
+merge_request: 8492
+author: Martin Cabrera