Input type FILE on HTML FORM not working on Safari Version 14.0.1 (14610.2.11.51.10)

I have run into the same issue yesterday.

Having looking into it I have found it working elsewhere and fixed it on the site I'm working on by adding an accept attribute with a file types list to the input tag. (e.g. <input type="file" accept=".xls,.xlsx,.xlsb,.txt,.csv,.tsv"/>)

Works fine now in Safari version 14.0.1 (14610.2.11.51.10) on Mojave 10.14.6

I confirm that this is a problem with Safari at least on Mojave. I have Safari 14.0.1 (14610.2.11.51.10) on Mojave 10.14.6 (18G6032 then 18G6042 after security update 2020-06: no change). It seems that no file upload will work: it fails on my own website with very simple html almost limited to <input type="file" />, and also fails on two standard CMS (an old WordPress and current MODX). There is no file selection window coming at all. I tried allowing anything (e.g. popup windows) : no change.

OS X's log indicates that Safari is denied file access when the button is clicked:

Sandbox: Safari(4721) deny(1) iokit-open AppleAPFSUserClient Violation: deny(1) iokit-open AppleAPFSUserClient

It is annoying for those maintaining a website were non-technical users have to provide files: they may conclude that the site is broken while it is not. I have no solution other than adding a warning suggesting to use another browser.

You can fix this is system settings > Security & Privacy > Full Disk Access. (May need to scroll down the left pane to find it).

Click the "+" and add /Applications/Safari, enable it, restart safari.