Introduction

Recently, I tried pushing to a remote repository in Git and ran into the following error:

error: RPC failed; HTTP 400 curl 22 The requested URL returned error: 400
send-pack: unexpected disconnect while reading sideband packet
fatal: the remote end hung up unexpectedly

I wondered if GitHub was down or if my network was unstable. However, after investigating, I found out that the cause was related to Git’s buffer size, and I managed to resolve it. Although it might be a basic issue, it was the first time I had seen this error, so I decided to write down what I learned about the cause and the solutions as a personal note.

Why does the error occur?

When Git sends diffs to a remote repository, it uses HTTPS or SSH. If you have files that are too large, or if you’re pushing a huge number of changes at once, the following can happen:

• High network load
• The connection might be interrupted mid-push, or the server might reject the request

Because of these reasons, the default settings may not handle the push correctly and can result in errors (especially over HTTPS).
Recommended Alternative Approaches & Settings

I haven’t tried all of these methods myself, but here are some solutions I found during my research.

1. Switch to SSH

Instead of HTTPS, using SSH can sometimes provide more stable communication.
If you’re using GitHub, register your SSH key and then change the remote URL like so:

git remote set-url origin git@github.com:<username>/<repository>.git

After that, run:

git push -u origin main

It often helps the push go more smoothly.

2. Use Git LFS (Large File Storage)

If you have a lot of large binary files (images, videos, assets, etc.), Git LFS is the officially recommended approach.
(Note: LFS stores large files in separate storage, and only pointers are kept in the Git repository.)

Example steps:

# Install LFS (the steps may vary depending on your environment)
git lfs install

# Specify which file extensions to track with LFS
git lfs track "*.mp4"

# Commit and push the changes
git add .gitattributes
git commit -m "Enable Git LFS"
git push origin main

This reduces the amount of data pushed at once, making errors less likely.

3. Break Down Your Commits

If you bundle a massive amount of changes into a single commit, the data pushed at once becomes very large. Therefore, splitting your commits or pushes into smaller chunks (e.g., by feature) can help avoid issues. If you already combined commits and are experiencing errors, you could use rebase or squash to reorganize the commits and then push in multiple parts.

4. Try the --no-thin Option

Git usually uses “thin pack” to efficiently send data. However, in some environments, this might cause errors.

You can disable thin pack with the following command:

git push --no-thin origin main

By prioritizing reliability over efficiency, this can sometimes stabilize the connection.

Tip: About the http.postBuffer Setting

In my case, the first solution I found was this, and it worked for me.
First, I ran a command to increase the buffer size:

git config --global http.postBuffer 524288000

Here, I set the buffer size to 500MB (524,288,000 bytes). Then I pushed again:

git push -u origin main

If the push succeeds without error, then it’s resolved.
Why does this solve the problem?

http.postBuffer defines the buffer size Git uses for sending data to the remote repository (the amount of data that can be sent at one time). By default, it’s 1MB, so when sending large amounts of data, it might stop mid-push. Increasing it to 500MB means you can send more data at once, allowing a smoother push.

Although this solution worked for me, later I discovered that in modern Git (2.9 and above), http.postBuffer is deprecated and can be ignored. Therefore, it seems recommended to try switching to SSH, using LFS, or breaking down commits first. If you happen to be using an older version of Git and encounter a similar error, it might be worth trying—but note that it’s not a permanent fix.

Conclusion

I’m not sure how common this error is, but since it was new to me, I wrote this summary as a reminder. I hope this blog post will help someone else facing push-related troubles.