Cannot open HTML files in Excel 2016 - Office 365 on Windows 10

I cannot open HTML files in Excel 2016 on Windows 10. These file open fine in Windows 8.1 with Office 365 / Excel. In basically an "out of the box" installation with all know updates being applied; nothing but Windows 10 and Office 365 installed essentially.

When I open an HTML file I get a blank screen in Excel as if no file is opened and there are no warning messages.


The Excel team has released a change in HTML/XLS file behavior in today’s security update for Excel 2010, 2013, and 2016. Excel will warn about the mismatch between the file extension and HTML content, but will now open the workbook in Protected View as an additional layer of security. If you trust the workbook, you can then enable editing. XLA and XLAM files are not part of this change, they will continue to not open in Excel.


How do I get the update? It depends on which version of Officeyou have.


Issue recap:

The Excel team has made a change in the behavior of certain file types to increase security. This change came in the security updates KB3115262, KB3170008, and KB3115322. Previously, when you tried to open an HTML, XLA, or XLAM file with an .XLS file extension from an untrusted location, Excel would warn about the mismatch between the file extension and content, but would still open the workbook without Protected View security. After the security updates Excel no longer will open the workbook because these files are not compatible with Protected View and there is no warning or other indication it was not opened.


Workarounds for .xla and .xlam files:


Thank you for your patience and input—community suggestions drove our decision to change this behavior in a way we hope will be much better for your workflows!

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Question Info

Last updated February 17, 2021 Views 5,889 Applies to: