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xlsx file not opening with Excel 2013 / 2010

HI , I am trying to download  zip file which is having Excel1.xlsx file . When I extract zip file tried to open excel its giving error "Excel cannot open the file Excel1.xlsx because the file format or extension is not valid" . before downloading Zip file I am creating writing data to excel compressing .

same thing If I am creating file with extension ".xls" its opening without any error message .



3 Replies

PM Prasanth M Syncfusion Team May 28, 2014 04:28 AM UTC

Hi Venkata,

Error Message- “file format or extension is not valid”:

If the file format is different than the extension then the MS Excel show the error “file format or extension is not valid”. Can you let me know whether you are generating the xlsx file using XlsIO with the Version property? Find the code snippet and online documentation link to change the workbook version using XlsIO.

Code Snippet to change the Workbook Version:

//Select the version to be saved

workbook.Version = ExcelVersion.Excel2007; //or

//workbook.Version = ExcelVersion.Excel2010;


//Save it as "Excel2007" format.



Online Documentation to change the Workbook Version:



If still the issue is reproducing then share us the code snippet which reproduces the issue.



PC Prashansha Chaurasia April 27, 2022 09:10 AM UTC


There are various ways to fix this error mentioned in the below article. Please visit the URL:


I hope it will fix the issue.  

Best Regards,


RS Ramya Sivakumar Syncfusion Team April 28, 2022 11:17 AM UTC


Thanks for sharing this, we will take a look at it



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