Error codes of the xUML Runtime are classified into:
| Log Errors | Log errors are errors that are not related to the implementation of a service. Log errors are written to the xUML service log and are indicating e.g. a configuration problem. They cannot be caught by the modeler. |
| System Errors | System errors are errors, thrown by the xUML Runtime, that can be caught by the modeler (see Catching Errors). A system error, that has not been caught, will be written to the xUML service log. |