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Firefox appending xls to xlxs files at time of downloading a file

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We are using a java application to download excel file but at the time of downloading Firefox itself appending .xls extension to the .xlsx file

We are using a java application to download excel file but at the time of downloading Firefox itself appending .xls extension to the .xlsx file

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That isn't a FF doing that is the site doing format if it comes with the newer MS extension then that is what it is. If you having problems from that site then you need to contact them about it.

Ilungisiwe ngu WestEnd

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We don't have the issue using other browsers like IE and Chrome. only with Firefox.

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I assume you mean JDK on the server sending HTML/JavaScript/CSS to Firefox, and not a Java plugin applet (which no longer runs after Firefox 52 Extended Support Release).

Do you know what content-type header the web app is sending for XLSX files? I think these are preferred:

  • XLS: "application/vnd.ms-excel"
  • XLSX: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"