I hope someone is able to assist in this issue:

In my organization I have end-users with Windows 7 Enterprise. During a pilot phase of Office 365 ProPlus coming from Office 2007, we have a particular user who is trying to open an .xml calendar that should open in Excel. While the user had Office 2007, she was prompted with an Open Document box that gave her the option to open as Read Only or Edit. If she selects Read Only the document opens in the IE11 Browser, if she selects Edit, after a few minutes it opens in Excel 2013.

On my machine I can open the document as Read Only and in Edit mode and the results are both in Excel 2013. 

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I have seen the file type association and on my machine it says:

C:\Windows\system32>ftype xmlfile xmlfile="C:\Program Files (x86)\Common Files\Microsoft Shared\OFFICE15\MSOXMLED.EXE" /verb open "%1"

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On her machine she has: 

C:\Windows\system32>ftype xmlfile xmlfile="C:\Program Files\Microsoft Office 15\Root\Client\AppVLp.exe" "C:\Program Files (x86)\Common Files\Microsoft Shared\OFFICE15\MSOXMLED.EXE" /verb open "%1"

I have gone into Control Panel --> Default Programs --> Associate a file type... and have changed the default program for .xml to be the Office XML Handler (MSOXMLED.EXE), used to be unknown application; and now the file opens in Notepad after the change has been made.

My team and I are currently trying to troubleshoot this issue before we deploy to Production. Does anyone have any ideas what could be causing this on other user's machines but not specifically on mine? 

Hi,

Could you please check if .xlxml under choose defaults for this program of excel is checked in users machine? If not, check this -> then restart IE -> Open the calendar again. Let me know if it works for you.

Let me know the result, thank you.