What happens when Mendix is not able to finish a transaction successfully without implemented Error Handling?

When Mendix encounters an issue during a transaction and there is no error handling implemented, the system stops the transaction. In this case, an error message is displayed to notify the user that something has gone wrong. This behavior is crucial for maintaining data integrity and providing immediate feedback to users about the status of their actions. By halting the transaction and showing an error message, Mendix ensures that users are informed of the failure, allowing them to take corrective measures or seek help, rather than proceeding under the assumption that their request was completed successfully. This mechanism helps prevent partial updates or data corruption, which could occur if transactions were allowed to go through without proper error checks.