Excel文件从报表查看器导出后出现错误

I had created the report using report viewer in asp.net. But recently I found that it happen some error when I tried to open the excel(xlsx) file after i download. It came out with the error message "We found a problem with some content in 'Reportest(34).xlsx'. Do you want us to try to recover as much as we can? If you trust the source of this workbook, click Yes.I had created the report using report viewer in