Bug: IE7 inappropriately changes a file's extension to .zip

Problem

There is a bug that causes IE7 to change the extensions of certain files to .zip when you are downloading them. Affected files include the new MS Office file formats (docx, xlsx, ...) and the Open Document formats used by Open Office (odt, ods, ...).

Two Client-Side Solutions

  1. Use Firefox 3 instead, it doesn't have this bug. I recommend you use Firefox anyway - it is more secure and has better features. Other browsers (Safari, Opera, Chrome, etc.) probably work too although I haven't tried them. Anything is better than IE.
  2. If you have to use IE, just rename the file after download, or use "Save as ..." (by right clicking on the link) to rename before download. The file downloads properly, only the extension has changed, so you just have to fix the extension.

Server-Side Solution

If you are running the server these files are stored on you can update the mime-types so that IE7 doesn't have this problem.

Download these values as a text file

Microsoft Office 2007 Formats 1
ExtensionMIME Type
docmapplication/vnd.ms-word.document.macroEnabled.12
docxapplication/vnd.openxmlformats-officedocument.wordprocessingml.document
dotmapplication/vnd.ms-word.template.macroEnabled.12
dotxapplication/vnd.openxmlformats-officedocument.wordprocessingml.template
ppsmapplication/vnd.ms-powerpoint.slideshow.macroEnabled.12
ppsxapplication/vnd.openxmlformats-officedocument.presentationml.slideshow
pptmapplication/vnd.ms-powerpoint.presentation.macroEnabled.12
pptxapplication/vnd.openxmlformats-officedocument.presentationml.presentation
xlsbapplication/vnd.ms-excel.sheet.binary.macroEnabled.12
xlsmapplication/vnd.ms-excel.sheet.macroEnabled.12
xlsxapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheet
xpsapplication/vnd.ms-xpsdocument
Open Document Formats 2
ExtensionMIME Type
odtapplication/vnd.oasis.opendocument.text
ottapplication/vnd.oasis.opendocument.text-template
odgapplication/vnd.oasis.opendocument.graphics
otgapplication/vnd.oasis.opendocument.graphics-template
odpapplication/vnd.oasis.opendocument.presentation
otpapplication/vnd.oasis.opendocument.presentation-template
odsapplication/vnd.oasis.opendocument.spreadsheet
otsapplication/vnd.oasis.opendocument.spreadsheet-template
odcapplication/vnd.oasis.opendocument.chart
otcapplication/vnd.oasis.opendocument.chart-template
odiapplication/vnd.oasis.opendocument.image
otiapplication/vnd.oasis.opendocument.image-template
odfapplication/vnd.oasis.opendocument.formula
otfapplication/vnd.oasis.opendocument.formula-template
odmapplication/vnd.oasis.opendocument.text-master
othapplication/vnd.oasis.opendocument.text-web

Download these values as a text file

References

  1. http://blogs.msdn.com/dmahugh/archive/2006/08/08/692600.aspx
  2. http://books.evc-cit.info/odbook/ch01.html#mimetype-table
    or http://framework.openoffice.org/documentation/mimetypes/mimetypes.html
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