Message type: E = Error
Message class:  5F - HR F: Error Messages (France) 
Message number: 602
Message text: Start date of period must be prior to end date
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The SAP error message 5F602 ("Start date of period must be prior to end date") typically occurs when there is an issue with the date range specified in a transaction or report. This error indicates that the start date you have entered is not earlier than the end date, which is a requirement for many processes in SAP.
Cause:
Incorrect Date Entry: The most common cause is that the user has mistakenly entered the start date as being later than or the same as the end date.
System Configuration: In some cases, the system configuration or settings may enforce date ranges that are not being adhered to.
Data Migration Issues: If data has been migrated from another system, there may be inconsistencies in the date formats or values.
Solution:
Check Date Inputs: Review the start and end dates you have entered. Ensure that the start date is indeed earlier than the end date.
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