Hello Joey,
Thank you for contacting support.
Could you please make sure that they are not opened in MS Outlook or any other program?
You may also try to zip a PST, if the file is in use, WinZip or Winrar will also show the same error message "cannot read abc.pst, because it is being used in another program".
Best Regards,
Saqib Razzaq
Support Developer, Aspose Sialkot Team
http://www.aspose.com
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