diff --git a/src/ros/action_server.cpp b/src/ros/action_server.cpp
index 380acd3..494d932 100644
--- a/src/ros/action_server.cpp
+++ b/src/ros/action_server.cpp
@@ -145,7 +145,11 @@ bool ActionServer::validateJoints(GoalHandle& gh, Result& res)
     return true;
 
   res.error_code = Result::INVALID_JOINTS;
-  res.error_string = "Invalid joint names for goal";
+  res.error_string = "Invalid joint names for goal\n";
+  res.error_string += "Expected: ";
+  std::for_each(goal_joints.begin(), goal_joints.end(), [&res](std::string joint){res.error_string += joint + ", ";});
+  res.error_string += "\nFound: ";
+  std::for_each(joint_set_.begin(), joint_set_.end(), [&res](std::string joint){res.error_string += joint + ", ";});
   return false;
 }
 
@@ -183,7 +187,7 @@ bool ActionServer::validateTrajectory(GoalHandle& gh, Result& res)
       }
       if (std::fabs(velocity) > max_velocity_)
       {
-        res.error_string = "Received a goal with velocities that are higher than " + std::to_string(max_velocity_);
+        res.error_string = "Received a goal with velocities that are higher than max_velocity_ " + std::to_string(max_velocity_);
         return false;
       }
     }
@@ -338,4 +342,4 @@ void ActionServer::trajectoryThread()
     has_goal_ = false;
     lk.unlock();
   }
-}
\ No newline at end of file
+}