It's an Error in prototype.js
Apparently, the error appeared because XMLHttpRequest isn’t allowed to set the Content-length header. It is set automatically by modern browsers. Mozilla Firefox now behaves the same way, just really old ones didn't. I solved the error by applying the following patch to the file sapphire/thirdparty/prototype/prototype.js
https://github.com/silverstripe/silverstripe-framework/commit/26a6f2e372ac6ef9601a53cac7fadc9ad87ab819
Posted to: Refused to set unsafe header "Connection" | Show Thread | Post Reply