A method is described for diagnosing errors within a production environment software platform that is arranged to process transaction messages and to store transaction history data related to processed transactions in a production database. The stored transaction history data comprises transaction objects that have been generated as the production environment software platform processes transaction messages. The method comprises detecting an error in a series of transaction messages processed by the production environment software platform, receiving the transaction history from the production database, the transaction history comprising a plurality of transaction objects, and configuring a development environment software platform to match the configuration of the production environment software platform at the start of the transaction history. The method further comprises running the development environment software platform with the received transaction history, and running a log file module to determine a source for the detected error.