Error messages

“Safari can’t connect to the server” on Mac

Safari found the address of the site, but the connection to the server did not open. DNS works. The server or the path to it fails.

Applies to: Safari on macOS 13 Ventura and later. The text was checked on macOS 27.2.Checked: 29 October 2026

Symptoms

Safari says: “Safari can’t open the page … because Safari can’t connect to the server …”.
Other sites open.
The address is a local server, such as localhost:3000, and the server does not run.

The server is down or refuses connections. Nothing listens on the port, or the server refuses the connection.
A local server that is not running. For a localhost address, your own server must run. See Port already in use on a Mac.
A firewall or filter. A firewall, a content filter or a company network can block the port.
A VPN or proxy. Traffic goes through a VPN or proxy that cannot reach the server.
A broken IPv6 path. The site has an IPv6 address, but IPv6 does not work on your network.

Open the same address on another device on the same network. If it fails there too, the problem is the network or the server.
Test the port from Terminal, with a 5-second timeout.
```
nc -vz -G 5 example.com 443
```
Request the page and show each step of the connection.
```
curl -v -o /dev/null https://example.com
```
Try IPv4 only, then IPv6 only. If only IPv6 fails, read IPv6 problems on a Mac.
```
curl -4 -I https://example.com
curl -6 -I https://example.com
```
For a local address, see if a server listens on the port.
```
lsof -nP -iTCP:3000 -sTCP:LISTEN
```

Reload the page after some minutes. A busy server can come back.
For a local server, start it. Then use the port that it prints.
If a VPN, proxy or security app is on, turn it off for a short test. Turn it on again after the test.
If only IPv6 fails, fix IPv6 or report it to your provider. See IPv6 problems on a Mac.
If a company network blocks the site, ask the administrator.

Kilobat's connection doctor tests the site layer by layer: network, proxy, DNS, rules, IPv4, IPv6, TLS and the server. It names the layer that failed.
```
kilobat why https://example.com
```
Show DNS, connect, TLS and first-byte times for one URL.
```
kilobat http-check https://example.com
```
These Kilobat checks are free. AI agents run them through MCP with diagnose_connection and diagnose_network. See Find why one site or API won't connect.

Why does Safari find the server but not connect?

Finding the server is DNS. Connecting is a separate step. Here DNS worked, and the connection failed.

Sources checked on 29 October 2026. Man pages are the ones installed with macOS; open one with man <name> in Terminal.