I installed ArcGIS 10.3 and I am unable to open any spreadsheets directly in ArcMap. Using the Excel to Table tool works fine. Is this new at 10.3 or am I missing something? You used to be able use the Add Data tool without converting it.
I was missing the 2007 Office System Driver: Data Connectivity Components. You can find them here:
After loading the connectivity components the add data works correctly. I had a later version of Office on my pc, but still needed to install these components.
Yes! You should download and install the 2007 Office System Driver: Data Connectivity Components. ArcGIS must need this specific version of the driver to be able to read xlsx files. Having a more recent version like Office 2013 would seem like it would have all of the previous drivers/components, but it doesn't. Click on the link shown above to get to the right driver.
I hope this helps!