Uploading an item update shows error

When I try to upload a zip file containing an item update, I get an error:
"Error (0%) and an infinite “working” icon…
The browser console shows “-3” from the source file: https://public-assets.envato-static.com/assets/market/pages/default/additional_scripts/uploading/index-ea7427dad0ad3ba364cc03ce14de210d0f46507422f5d96c796b7db12c9d4d25.js

This is the error, someone is getting the same error? Any advice? I tried also the FTP service with FileZilla, but there I get a connection error, without other details.