diff --git a/devops-service/app/api2/handlers/stack_template.rb b/devops-service/app/api2/handlers/stack_template.rb
index 0e37173..735b617 100644
--- a/devops-service/app/api2/handlers/stack_template.rb
+++ b/devops-service/app/api2/handlers/stack_template.rb
@@ -30,7 +30,30 @@ module Devops
         end
 
         def delete_stack_template id
-          Devops::Db.connector.stack_template_delete id
+          envs_with_this_template = envs_using_stack_template(id)
+
+          if envs_with_this_template.empty?
+            Devops::Db.connector.stack_template_delete id
+          else
+            raise ConflictException.new("Stack template '#{id}' is already in use in #{envs_with_this_template.join(', ')}")
+          end
+        end
+
+        private
+
+        def envs_using_stack_template(id)
+          projects = Devops::Db.connector.projects_all
+          envs_with_this_template = []
+
+          projects.each do |project|
+            project.deploy_envs.each do |env|
+              next unless  env.respond_to?(:stack_template)
+              if env.stack_template == id
+                envs_with_this_template << "#{project.id}-#{env.identifier}"
+              end
+            end
+          end
+          envs_with_this_template
         end
 
       end