What does ERR_CONNECTION_CLOSED mean?

The browser connected to the server, and the server closed the connection before it sent a page. The server decided to close it, or something between you and the server did.

What is the difference between ERR_CONNECTION_CLOSED and ERR_CONNECTION_RESET?

Both mean the connection ended too early. A reset is a sudden end, often caused by a crash or a rule that cuts the connection. A close is an orderly end, so it points more often to a setting such as the wrong port or a TLS mismatch.

Why does ERR_CONNECTION_CLOSED appear on a new HTTPS site?

The server may not serve TLS on port 443 yet, the certificate may not be set up, or a proxy in front may speak another protocol. Check the port with an SSL checker.

How do I fix ERR_CONNECTION_CLOSED as a visitor?

Check the address, try another network and browser, turn off a VPN or proxy, and check the clock of your device. If the site fails everywhere, only the site owner can fix it.

ERR_CONNECTION_CLOSED

ERR_CONNECTION_CLOSED: what it means and how to fix it

ERR_CONNECTION_CLOSED means the server closed the connection before it sent a page. Unlike a reset, the connection ends in an orderly way, so the cause is often a setting: an HTTPS request to a plain HTTP port, a TLS mismatch, or a rule in a proxy or firewall.

You may also see

“This page isn’t working. The server unexpectedly closed the connection” (Chrome)

Common causes

1
An HTTPS request goes to a port that serves plain HTTP, or the other way round, and the server closes the connection.
2
The browser and the server do not share a TLS version or a cipher, so the handshake ends.
3
A proxy, a load balancer or a firewall closes connections that match a rule, or that exceed a limit.
4
The server is overloaded and closes new connections, or its process has hit a limit.
5
A VPN, a proxy or a security program on the device interferes with the connection.

If you are visiting the site: how to fix it

1
Check that the address starts with the right scheme and port: https:// for secure sites. Try http:// only if you know the site is not secure.
2
Try another network and another browser.
3
Turn off a VPN and a proxy, then clear the browser cache and cookies for the site.
4
Check that the date and time of your device are right, because a wrong clock breaks secure connections.

If you run the site: what to check

1
Check what answers on the port: a TLS server on 443, and plain HTTP on 80. A site that listens for HTTP on 443 closes every HTTPS connection.
2
Check the TLS versions and the ciphers of the server. Allow TLS 1.2 and TLS 1.3.
3
Check the rules and the limits of the proxy, the load balancer and the firewall in front of the site.
4
Check the load and the limits of the server: open file limits, worker counts and memory.

Check it with free tools

Frequently asked questions

What does ERR_CONNECTION_CLOSED mean?: The browser connected to the server, and the server closed the connection before it sent a page. The server decided to close it, or something between you and the server did.
What is the difference between ERR_CONNECTION_CLOSED and ERR_CONNECTION_RESET?: Both mean the connection ended too early. A reset is a sudden end, often caused by a crash or a rule that cuts the connection. A close is an orderly end, so it points more often to a setting such as the wrong port or a TLS mismatch.
Why does ERR_CONNECTION_CLOSED appear on a new HTTPS site?: The server may not serve TLS on port 443 yet, the certificate may not be set up, or a proxy in front may speak another protocol. Check the port with an SSL checker.
How do I fix ERR_CONNECTION_CLOSED as a visitor?: Check the address, try another network and browser, turn off a VPN or proxy, and check the clock of your device. If the site fails everywhere, only the site owner can fix it.

Know about it before your visitors do

Uptrack checks your site on a schedule from several locations and alerts you when it stops answering, so you hear about it from an alert and not from a customer.

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