What is the reason for the system prompt 'Fatal Error: Database Inconsistency (TODAY)'?

Due to the frequent use of date modification by operators for daily settlement of past dates. This inevitably leads to forgetting to modify the date back to the current day. Once the date is not changed back to the same day before entering the system to sell electricity, it will immediately lead to the occurrence of this error. After an error occurs, you should immediately exit the system, change the date to the correct date of the day, and then enter the system to work.