Why Did Git Push Suddenly Stop Working

Today I ran into a bizarre problem during development — git push worked perfectly yesterday, but suddenly stopped working today.

The error messages looked like this:

ERROR: no healthy upstream
fatal: Could not read from remote repository.
 
Please make sure you have the correct access rights
and the repository exists.

Or this one:

ERROR: upstream connect error or disconnect/reset before headers.
remote connection failure, transport failure reason: delayed connect error: Connection refused
fatal: Could not read from remote repository.

At first, I thought maybe GitHub was down, or perhaps my SSH key expired. But everything checked out fine:

ssh -T [git@github.com](mailto:git@github.com)

Output:

Hi shenlu89! You've successfully authenticated, but GitHub does not provide shell access.

Then I checked the remote URL:

git remote -v
origin  [git@github.com](mailto:git@github.com):shenlu89/docs.git (fetch)
origin  [git@github.com](mailto:git@github.com):shenlu89/docs.git (push)

• SSH connection worked ✔️
• Repository URL correct ✔️
• SSH keys valid ✔️
• git remote -v looks fine ✔️

So where was the problem?

SSH Works, but git push Fails — Why?

Normally, if you're pushing over SSH, then:

• If ssh -T git@github.com works
• git push should also work

But in my case:

• ssh -T → works
• git push → fails

This means the issue was not SSH itself, but something interfering with Git’s network connection.

Checking macOS Network Proxy Settings

I checked the system proxy configuration:

networksetup -getwebproxy "Wi-Fi"
networksetup -getsocksfirewallproxy "Wi-Fi"

The result:

Enabled: Yes
Server: 127.0.0.1
Port: 7890

In other words:

• macOS had system-wide HTTP/HTTPS/SOCKS proxies enabled
• Everything was routed to 127.0.0.1:7890
• But the local proxy software wasn’t running
• So any request going through the proxy → connection refused

This perfectly explains the behavior:

Why SSH test worked

The ssh -T command does not use macOS system proxies.

Why git push failed

Git’s SSH operations can be affected by system proxy settings. When the proxy is misconfigured or inactive, connections fail immediately.

The Fix: Disable macOS System Proxies

Turning off all system-level proxies solved the issue:

networksetup -setwebproxystate "Wi-Fi" off
networksetup -setsecurewebproxystate "Wi-Fi" off
networksetup -setsocksfirewallproxystate "Wi-Fi" off

Then:

git push

And everything worked instantly.

Bonus Tip: Use GitHub SSH Over Port 443 (More Reliable)

To avoid similar issues in networks that block port 22 (corporate WiFi, school networks, hotels, etc.), I also updated my SSH config to use GitHub’s 443 tunnel.

Edit ~/.ssh/config:

Host github.com
    HostName ssh.github.com
    Port 443
    User git
    IdentityFile ~/.ssh/id_ed25519
    IdentitiesOnly yes

Port 443 is almost never blocked, and usually bypasses proxies as well — making Git operations much more stable.

Conclusion

This debugging journey taught me:

• SSH tests don't always reflect how Git uses SSH internally
• macOS system proxies can silently break Git push
• Port 443 is a safer choice for GitHub SSH

If your git push works one day and fails the next, make sure your system proxy settings aren’t hijacking your SSH traffic.

Happy coding!