Do you see this message when opening a workbook on this forum, or on your own PC? I see it on this forum all the time; it happens when someone uploads a workbook named something.xlsx. This board renames it something.xlsx.xls, and then when I open it I get a warning message because it's named .xls but it's actually an .xlsx.

The board software does not rename files. What sometimes happens is that people who have the Windows Explorer 'Hide extensions for known file types' option checked add their own extensions (which actually become part of the filename, not its true extension). When such files get uploaded, the true extension is revealed.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

I'm willing to stand corrected ... but I don't think I get it yet. I just selected and uploaded two workbooks, one named x.xls and the other x.xlsx. I selected them both simply by clicking on them in the File-Upload dialog; I didn't type anything additional in the filename text box. When I open the first, it opens normally in my Excel 2010 without complaint. When I click on the second, I get this message: "The file you are trying to open, 'x.xlsx-1.XLS', is in a different format than the one specified by the file extension...." and so on. When I open that one anyway and then offer to save it, it wants to save it as "Copy of x.xlsx-1.xlsx".

I may be mistaken about what MSOfficeForums.com is doing, but it seems to me it's surely doing something that isn't completely correct.

Attached Files

	x.xls (153.0 KB, 12 views)
	x.xlsx (11.9 KB, 14 views)

Things are exactly the same for me as for Bob. When I open files on other forums ( EF, CC, MrE,Ozgrid, Excelguru) the files always open normally.
Very strange

__________________
Using O365 v2503 - Did you know you can thank someone who helped you? Click on the tiny scale in the right upper hand corner of your helper's post