When using Excel files as a data source in the Jet Data Manager, it is possible that a user has the Excel file open while an execution package is running which will cause the execution package to fail due to the user having an exclusive lock on the file. This exclusive lock prevents other user (including the Jet Data Manager) from accessing the file and will therefore cause the execution routine to fail.
There are two methods to avoid the execution package failing if the Excel file is open.
Set the Excel data source to be allowed to fail. This is covered in the KB article here: How to Allow a Data Source to Fail During Execution
Enable sharing mode in the Excel file to prevent an exclusive lock from occurring.
This can be done by navigating to Review -> Share Workbook in Excel:
The user should then check the box to allow changes by more than one user at a time:
The user can then click OK to enable sharing privileges on the file which should prevent an exclusive lock from occurring when it is open.