| Cause | An invalid protocol was used. |
| Action | Ensure the protocol exists and the message transmission sequence is correct. |
| Cause | The procedure was successfully invoked. |
| Action | Check the result. |
| Cause | The library path is invalid. |
| Action | Check the library path. |
| Cause | The specified function was not found in the library. |
| Action | Check the function name. |
| Cause | Failed to execute an external function. |
| Action | Investigate the cause of the failure and try again. |
| Cause | The specified class was not found in the specified class path. |
| Action | Check the class name and path. |