User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36 Steps to reproduce: Pre-reqs: macOS 10.14 Mojave Firefox 62.0.2 64 bit Macbook Pro 2017 1. Open standard file upload frame (for examples, Upload file to Google Drive) 2. Select any file 3. Click upload button Actual results: Browser is completely stuck Can be closed only by Force quit The problem started after update to the Mojave Private browsing doesn't solve the problem Expected results: Successful file fetch

Thanks for filing, duplicate of Bug 1489785.