GitHub SSH Not Working Today? The 4 November ssh-rsa Brownout

If git push, git pull or git clone over SSH suddenly failed on 4 November 2026, your code and your access are probably fine. GitHub ran a planned “brownout”: a temporary switch-off of old SSH security methods, so anyone still using them notices before they are removed for good.

What GitHub is changing

In its 22 September 2026 changelog, GitHub announced it is removing two older SSH methods:

• The ssh-rsa signature type, which signs with SHA-1. This is not the same as removing RSA keys. A modern client can keep using an RSA key with the newer rsa-sha2-256 or rsa-sha2-512 signatures.
• The diffie-hellman-group-exchange-sha256 key exchange method.

GitHub has also said that new RSA keys added from 14 October 2026 must be at least 3072 bits long.

Key dates

• 4 November 2026: first brownout
• 9 December 2026: second brownout
• 13 January 2027: permanent removal

Is it the brownout or a real GitHub outage?

First check githubstatus.com. If GitHub reports an incident, wait for it to clear. If the status is green, but other people’s SSH still works and yours does not, your client or key is using one of the old methods.

Run this test:
ssh -T git@github.com
A working setup replies “Hi <username>! You’ve successfully authenticated”. For details, run it with -vv and read the lines that say why the connection failed.

Error messages you may see

• Permission denied (publickey): your key was not accepted. This can be the brownout, or simply the wrong key or account.
• no mutual signature algorithm: your client only offered the old SHA-1 signature.
• no matching key exchange method found: your client only offered the removed key exchange method.
• Unable to negotiate: common in CI logs; same causes as above.

How to fix it

1. Update your SSH and Git client

Any reasonably recent OpenSSH (version 7.2 or later) supports the newer RSA signatures. Update Git for Windows, macOS, or your Linux packages first. This alone fixes most cases.

2. Switch to an Ed25519 key

Ed25519 keys are short, fast and not affected by this change. Create one:
ssh-keygen -t ed25519 -C "you@company.com"
Then add the new public key (~/.ssh/id_ed25519.pub) under GitHub → Settings → SSH and GPG keys, and test again with ssh -T git@github.com.

3. Remove old overrides from your SSH config

Look in ~/.ssh/config and /etc/ssh/ssh_config for lines that force old algorithms, such as PubkeyAcceptedAlgorithms +ssh-rsa, HostKeyAlgorithms +ssh-rsa or a KexAlgorithms line naming diffie-hellman-group-exchange-sha256. Remove them unless another server truly needs them.

4. Check CI, deploy keys and tools

Build servers, deploy keys, IDE plugins and older SSH libraries are the most common places old methods hide. Test each pipeline before 13 January 2027.

Need to ship right now?

Switch the remote to HTTPS for the day: run git remote set-url origin https://github.com/OWNER/REPO.git and sign in with a personal access token. Fix SSH properly afterwards.

What to do before January

Treat today as a free warning. Update clients, move the team to Ed25519 keys, and test every pipeline before the 9 December brownout, so the permanent change on 13 January 2027 passes without anyone noticing.

Source: GitHub Changelog, “Security improvements for SSH” .