diff --git a/devops-service/app/api2/handlers/project.rb b/devops-service/app/api2/handlers/project.rb
index ee45024..e82616c 100644
--- a/devops-service/app/api2/handlers/project.rb
+++ b/devops-service/app/api2/handlers/project.rb
@@ -119,11 +119,11 @@ module Devops
           begin
             unless env.identifier == deploy_env
               servers = Devops::Db.connector.servers_by_project_and_deploy_env(id, deploy_env)
-              raise InvalidRecord.new("Can not update environment '#{deploy_env}', there are #{servers.size} servers on it") unless servers.empty?
+              raise InvalidRecord.new("Environment '#{deploy_env}' can't be updated: it has #{servers.size} running servers.") unless servers.empty?
             end
             begin
               project.deploy_env(env.identifier)
-              raise InvalidRecord.new("Can not change environment '#{deploy_env}' to '#{env.identifier}', environment '#{env.identifier}' already exist") unless deploy_env == env.identifier
+              raise InvalidRecord.new("Environment '#{deploy_env}' can't be renamed to '#{env.identifier}', environment '#{env.identifier}' already exists") unless deploy_env == env.identifier
             rescue RecordNotFound => e
             end
             env.validate!
@@ -185,13 +185,15 @@ module Devops
 
         def delete_project id
           deploy_env = parser.delete
-          servers = Devops::Db.connector.servers id
-          raise DependencyError.new "Deleting #{id} is forbidden: Project has servers" if !servers.empty?
           project = Devops::Db.connector.project(id)
-          info = if deploy_env.nil?
+          if deploy_env.nil?
+            servers = Devops::Db.connector.servers id
+            raise DependencyError.new "Deleting project #{id} is forbidden: Project has servers" unless servers.empty?
             project.delete
             "Project '#{id}' is deleted"
           else
+            servers = Devops::Db.connector.servers id, deploy_env
+            raise DependencyError.new "Deleting deploy_env #{deploy_env} is forbidden: Project has servers" unless servers.empty?
             project.delete_deploy_env(deploy_env)
             "Project '#{id}'. Deploy environment '#{deploy_env}' has been deleted"
           end
diff --git a/devops-service/exceptions/response_error.rb b/devops-service/exceptions/devops_error.rb
similarity index 100%
rename from devops-service/exceptions/response_error.rb
rename to devops-service/exceptions/devops_error.rb