I am trying to transfer some MP4 files from a hard drive that is hooked up to my MacBook Air to my dropbox account. My laptop is connected to the internet via a USB LAN cable. There are 9TB of space left on my account. I have already successfully uploaded files that are anywhere from 2-9GB large this way, but when I try to upload the 20GB file, it uploads all the way until "1 second left" and then gets stuck. The file name for the 20GB is very similar to the names of the files that were uploaded successfully, so I don't think it's a file name error. I'm also doing this through the dropbox website, not the Macbook extension. Any suggestions?
To rule out any issues with the browser itself, can you try using a different web browser to upload the file? If this results in the same behaviour, please then try using an incognito/private window too.
Finally, if the above doesn't resolve the issue then you can try clearing the browser cache and ensuring there aren’t any pending updates for your browser.