If you are trying to upload something or perhaps you are doing certain operation on your site and you end up with an error ‘err_connection_reset normally it happens in chrome the possible cause of this could be your server .
What err_connection_reset means ?
This means that entire process has died without any response from client and connection was closed due to some security system set by hosting provider/server, it could also be segments fault on your server, so if it happens you might want to contact your hosting provider for further investigation on this issue and possible fix.
You can also try by disabling proxy or firewall in your local computer if you are using any it can cause such issue as well. if this isn’t the case then aforementioned reason is the actual cause of the issue.