Hi Jaeyeol Shin,
Thank you for using the Syncfusion products.
We are able to reproduce the issue "OverflowException when opening the file" in version 10.2.0.75. But, we have fixed this issue in our latest version 11.2.0.25v. We have attached the screen shot for this. We strongly recommend you to upgrade your version to the latest one which has more enhancements and improved in performance.
Video Screen Shot: OverFlow.zip
You can download the latest version from the following link.
http://www.syncfusion.com/downloads/latest-version
Kindly let us know if you need any clarification.
Regards,
Rajesh A