The error, which usually comes with the 101 code, is particularly common on Chrome (Google’s browser), but Firefox, Internet Explorer, etc. also display similar error messages such as “The connection was reset” which indicate a connection problem. In contrast to HTTP error messages, for example, the “ERR_CONNECTION_RESET” message does not directly indicate whether the problem is caused by the client, the server, or the network.
Technically speaking, when connecting to the desired web project, your browser only receives a FIN packet (finish) instead of the regular reply package. This is used by the Transmission Control Protocol (TCP), the web’s standard transport protocol, to announce the end of a connection to the client. Normally, however, the FIN packet is preceded by a previously established connection over a certain period, which is not the case with an “ERR_CONNECTION_RESET” error.