Photo by Pankaj Patel on Unsplash

So there I was, pulling down the latest changes from a remote repo right before a code review, and git fetch just... died on me. No helpful message, just a vague failure and that sinking feeling. If you've landed here because git fetch failed and you're not sure why, you're in the right place — I've debugged this thing more times than I'd like to admit.

The frustrating part about this error is that it can mean about five different things depending on your setup. SSH key issue? Network problem? Corrupted local repo? All of them can produce basically the same output. Let's break it down.

What the Error Actually Looks Like

Most of the time you'll see something along these lines in your terminal:

$ git fetch origin
fatal: unable to connect to github.com:
github.com[0: 140.82.121.4]: errno=Connection refused

error: Could not fetch origin

Or if it's an SSH authentication issue, it usually shows up like this:

$ git fetch origin
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

And occasionally you'll just get the cryptic cousin:

error: RPC failed; curl 56 OpenSSL SSL_read: Connection was reset

That last one is particularly fun at 11pm. Anyway — different messages, but most trace back to the same handful of root causes.

Why git fetch Fails

Honestly, the majority of cases I've seen come down to three things: your SSH key isn't set up correctly (or expired, or not added to the agent), your network is blocking the connection, or the remote URL in your local config is wrong — sometimes after a repo gets renamed or migrated. There's also a less common case where the local repo itself gets corrupted, usually after a bad disk write or a forced shutdown during a fetch. That one's rarer but nasty when it happens.

Fix 1: Check and Re-add Your SSH Key

This is the fix that resolves it probably 60% of the time in my experience. First, test your SSH connection directly:

ssh -T git@github.com

If you get Permission denied (publickey), your SSH agent either doesn't have your key loaded or the key isn't registered with GitHub. Fix it like this:

# Start the SSH agent
eval "$(ssh-agent -s)"

# Add your key (default path — adjust if yours is different)
ssh-add ~/.ssh/id_ed25519

Then test again with ssh -T git@github.com. You should see something like Hi username! You've successfully authenticated... If you do, try your fetch again — it'll probably work now.

One thing worth mentioning: if you recently regenerated your SSH key or got a new machine, you have to re-upload the public key to GitHub under Settings → SSH and GPG keys. I've seen people spend an hour troubleshooting before realizing they just forgot that step after setting up a new laptop.

Fix 2: Verify (and Correct) the Remote URL

Here's the thing though — sometimes the SSH connection is fine and the issue is just that the remote URL is stale or wrong. Repos get renamed, organizations change, and your local .git/config has no idea.

Check what remote URL you're currently pointing at:

git remote -v

You'll see something like:

origin  git@github.com:oldname/repo.git (fetch)
origin  git@github.com:oldname/repo.git (push)

If that URL is outdated, update it:

git remote set-url origin git@github.com:newname/repo.git

Or if you want to switch from SSH to HTTPS (sometimes useful if you're behind a corporate firewall that blocks port 22):

git remote set-url origin https://github.com/username/repo.git

Then run git fetch origin again. Nine times out of ten if it was a URL problem, this is all you need.

Fix 3: Increase the HTTP Buffer Size (for RPC/curl errors)

Now here's where it gets tricky — if you're seeing that RPC failed; curl 56 type of error, it's usually a buffer size issue, especially on repos with a large history or a lot of LFS objects. Git's default HTTP post buffer is pretty small and it just chokes mid-transfer.

git config --global http.postBuffer 524288000

That sets it to 500MB. You can also try fetching with a shallower depth as a workaround:

git fetch --depth=1 origin

This won't get you the full history, but it'll at least let you pull down the latest state of the branch. You can always deepen it later with git fetch --unshallow once you're on a better connection.

Fallback: Nuke the Remote and Re-add It

Alright so if none of the above worked, here's the scorched-earth fallback that I keep in my back pocket. Sometimes the remote tracking config just gets into a weird state and the cleanest thing is to remove and re-add the remote entirely:

# Remove the existing remote
git remote remove origin

# Re-add it fresh
git remote add origin git@github.com:username/repo.git

# Fetch again
git fetch origin

This is also worth trying after a repo migration or if someone force-pushed to main and your local refs are now out of sync. It's blunt, but it works.

If your local repo itself is corrupted — you'll usually know because git fsck spits out a wall of errors — honestly the fastest path is just re-cloning. Back up any uncommitted work with git stash first if you can, or just copy the modified files out manually, then clone fresh.

git fsck --full

Run that and see what it says. If it's all clean, the problem is definitely on the network or auth side.

Quick tip before you close this tab: if you're on a Mac and recently updated macOS, your SSH keys sometimes get dropped from the keychain. Run ssh-add --apple-use-keychain ~/.ssh/id_ed25519 to get them persistent again. Caught me off guard after a Sonoma update last year and I wasted a solid 20 minutes on it.

Hope this saves you some time — or at least saves you from staring at a blinking cursor at midnight wondering why git hates you.

Related: How to Fix "git error: cannot lock ref" (And Why It Keeps Coming Back)