How to fix error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received. in Git

GitINTERMEDIATEMEDIUM

The 'RPC failed; curl 56 GnuTLS' error occurs during Git operations over HTTPS when there's a TLS/SSL communication failure. This is commonly caused by network issues, large repository transfers, or GnuTLS library problems on Linux systems.

What this error means

The "RPC failed; curl 56 GnuTLS recv error" message indicates that Git's HTTP transfer failed due to a TLS (Transport Layer Security) communication problem. The error code 56 refers to curl's CURLE_RECV_ERROR, meaning data could not be received from the remote server. Git uses the curl library for HTTPS operations, and on many Linux distributions (particularly Ubuntu and Debian), curl is compiled with GnuTLS rather than OpenSSL for SSL/TLS support. GnuTLS can sometimes be more sensitive to network issues or have compatibility problems with certain server configurations. The specific GnuTLS error code (like -9 for unexpected packet length, -110 for improper termination, or -54 for pull function errors) provides additional context. These errors typically occur during clone, push, pull, or fetch operations, especially with large repositories or over unstable network connections.

How to fix "error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received."

1Increase Git HTTP buffer size

The most common fix is to increase Git's HTTP buffer size. By default, Git uses a relatively small buffer which can cause issues with large repositories:

bash

# Increase buffer to 500 MB
git config --global http.postBuffer 524288000

# For very large repositories, try 1 GB
git config --global http.postBuffer 1048576000

After setting this, retry your Git operation. Note that this increases memory usage during Git HTTP operations.

2Use shallow clone for large repositories

If you're cloning a large repository, try a shallow clone to reduce the amount of data transferred:

bash

# Clone with limited history
git clone --depth 1 https://github.com/user/repo.git

# If you need more history later, unshallow
cd repo
git fetch --unshallow

This downloads only the latest commit initially, which is much less data and reduces the chance of TLS errors.

3Enable verbose output for debugging

Enable Git's debugging output to get more information about where the failure occurs:

bash

# Set environment variables for verbose output
export GIT_TRACE_PACKET=1
export GIT_TRACE=1
export GIT_CURL_VERBOSE=1

# Now run your git command
git clone https://github.com/user/repo.git

This will show detailed information about the HTTP/TLS communication and help identify the exact point of failure.

4Use SSH instead of HTTPS

Switching from HTTPS to SSH bypasses GnuTLS entirely and often resolves the issue:

bash

# Clone using SSH instead of HTTPS
git clone [email protected]:user/repo.git

# For existing repositories, change the remote URL
git remote set-url origin [email protected]:user/repo.git

You'll need to set up SSH keys if you haven't already:

bash

# Generate SSH key (if you don't have one)
ssh-keygen -t ed25519 -C "[email protected]"

# Add key to ssh-agent
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

# Copy public key to add to GitHub/GitLab
cat ~/.ssh/id_ed25519.pub

5Update Git to the latest version

Older Git versions may have known GnuTLS-related bugs. Update to the latest version:

bash

# Ubuntu/Debian - add Git PPA for latest version
sudo add-apt-repository ppa:git-core/ppa
sudo apt update
sudo apt install git

# Fedora/RHEL
sudo dnf upgrade git

# macOS
brew upgrade git

# Check version
git --version

6Configure Git to use OpenSSL instead of GnuTLS

If the issue persists, you can configure Git to use OpenSSL as the SSL backend (if available):

bash

# Check available SSL backends
git config --global --list | grep ssl

# Set OpenSSL as the backend (if installed)
git config --global http.sslBackend openssl

If your system doesn't have OpenSSL support in Git, you may need to reinstall Git with OpenSSL. On Ubuntu:

bash

# Install build dependencies
sudo apt-get install build-essential libcurl4-openssl-dev libexpat1-dev gettext libz-dev libssl-dev

# Download and compile Git with OpenSSL (advanced)
wget https://github.com/git/git/archive/v2.43.0.tar.gz
tar -xzf v2.43.0.tar.gz
cd git-2.43.0
make prefix=/usr/local NO_GNUTLS=1 all
sudo make prefix=/usr/local install

7Check for network issues and proxies

Network configuration issues can cause TLS failures. Check your network setup:

bash

# Check if proxy is configured
git config --global --get http.proxy
git config --global --get https.proxy

# Temporarily unset proxy to test
git config --global --unset http.proxy
git config --global --unset https.proxy

# If behind corporate proxy, ensure it's configured correctly
git config --global http.proxy http://proxy.company.com:8080

If you're on a corporate network with TLS inspection, you may need to add the corporate CA certificate:

bash

# Add corporate CA certificate
git config --global http.sslCAInfo /path/to/corporate-ca.crt

8Disable SSL verification (temporary workaround)

As a last resort for testing, you can temporarily disable SSL verification. Warning: This is insecure and should not be used for production!

bash

# Disable SSL verification temporarily (NOT RECOMMENDED for production)
git config --global http.sslVerify false

# Run your git command
git clone https://github.com/user/repo.git

# Re-enable SSL verification immediately after
git config --global http.sslVerify true

Only use this to confirm the issue is TLS-related. Never leave SSL verification disabled as it exposes you to man-in-the-middle attacks.

How to fix error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received. in Git

What this error means

Typical symptoms

Common causes

How to fix "error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received."

Advanced notes

Related errors

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