diff --git a/rcl_action/include/rcl_action/types.h b/rcl_action/include/rcl_action/types.h
index 783165b..dee4c23 100644
--- a/rcl_action/include/rcl_action/types.h
+++ b/rcl_action/include/rcl_action/types.h
@@ -93,6 +93,11 @@ typedef int8_t rcl_action_goal_state_t;
 #define GOAL_STATE_ABORTED action_msgs__msg__GoalStatus__STATUS_ABORTED
 #define GOAL_STATE_NUM_STATES 7
 
+/// User friendly error messages for invalid trasntions
+// Description variables in types.c should be changed if enum values change
+extern const char * goal_state_descriptions[];
+extern const char * goal_event_descriptions[];
+
 /// Goal state transition events
 typedef enum rcl_action_goal_event_t
 {
diff --git a/rcl_action/src/rcl_action/goal_handle.c b/rcl_action/src/rcl_action/goal_handle.c
index e456042..f86f96c 100644
--- a/rcl_action/src/rcl_action/goal_handle.c
+++ b/rcl_action/src/rcl_action/goal_handle.c
@@ -89,9 +89,9 @@ rcl_action_update_goal_state(
     goal_handle->impl->state, goal_event);
   if (GOAL_STATE_UNKNOWN == new_state) {
     RCL_SET_ERROR_MSG_WITH_FORMAT_STRING(
-      "goal_handle attempted invalid transition from state %d with event %d",
-      goal_handle->impl->state,
-      goal_event);
+      "goal_handle attempted invalid transition from state %s with event %s",
+      goal_state_descriptions[goal_handle->impl->state],
+      goal_event_descriptions[goal_event]);
     return RCL_RET_ACTION_GOAL_EVENT_INVALID;
   }
   goal_handle->impl->state = new_state;
diff --git a/rcl_action/src/rcl_action/types.c b/rcl_action/src/rcl_action/types.c
index 4e6ce33..03c9cbe 100644
--- a/rcl_action/src/rcl_action/types.c
+++ b/rcl_action/src/rcl_action/types.c
@@ -132,6 +132,13 @@ rcl_action_cancel_response_fini(rcl_action_cancel_response_t * cancel_response)
   return RCL_RET_OK;
 }
 
+/// Values should be changed if enum values change
+const char * goal_state_descriptions[] =
+{"UNKNOWN", "ACCEPTED", "EXECUTING", "CANCELING", "SUCCEEDED", "CANCELED", "ABORTED"};
+
+const char * goal_event_descriptions[] =
+{"EXECUTE", "CANCEL_GOAL", "SUCCEED", "ABORT", "CANCELED", "NUM_EVENTS"};
+
 #ifdef __cplusplus
 }
 #endif