Firewalls or proxies between you and the video file might be stripping away version information or forcing a version the server doesn't like. How to Fix the 505 MP4 Error For Viewers
In the world of digital media, there is nothing more frustrating than a video that refuses to load. While most users are familiar with the dreaded "404 Not Found," a more cryptic error——can occasionally disrupt the delivery of MP4 files, especially in professional or legacy web environments. 505 mp4
The player may continually try to reconnect using an unsupported protocol, leading to endless loading icons. Common Causes Firewalls or proxies between you and the video