Windows users will scoff at this, but renaming a file in a File Upload dialog box on Mac is a surprisingly obscure action. Renaming is not available in the context menu, nor does the usual shortcut work.
To rename a file in a regular Finder window, you can select it and hit the Enter key. However, you can’t do this in a File Upload dialog as the Enter key has a different meaning.
To rename a file, select it, hit Cmd+I, open up the Name & Extension pane, and change the name.
Leo on Tech 
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