git fatal error: Unsupported SSL backend 'schannel'

Resolving 'git fatal error: Unsupported SSL backend 'schannel'' on Windows and WSL

This article guides you through diagnosing and fixing the 'Unsupported SSL backend 'schannel'' error in Git, commonly encountered on Windows and WSL environments, ensuring your Git operations are secure and functional.

The error message git fatal error: Unsupported SSL backend 'schannel' indicates that Git is configured to use the 'schannel' SSL backend, which is a Windows-specific implementation, but it's either not available or improperly configured in the current environment. This often happens when Git is installed or configured in a way that conflicts with the operating system's expectations, especially in Windows Subsystem for Linux (WSL) environments or after certain system updates. Understanding the underlying cause is key to a permanent fix.

Understanding SSL Backends in Git

Git can be compiled and configured to use different SSL/TLS backends for secure communication (e.g., HTTPS cloning, pushing, and pulling). The most common backends are:

• OpenSSL: A widely used, open-source cryptographic library. It's the default on most Linux and macOS systems.
• schannel: Microsoft's native SSL/TLS implementation, primarily used on Windows.
• LibreSSL: A fork of OpenSSL.

When you encounter the 'schannel' error, it means Git is trying to use the Windows-native backend in a context where it's not supported or properly initialized. This is particularly prevalent in WSL, where the Linux Git binary might be attempting to use a Windows-specific configuration.

Diagnosing the Issue

Before attempting a fix, it's crucial to identify the current Git configuration related to SSL. You can inspect your global and system Git configurations to see which SSL backend is set.

First, check your Git version and its configured SSL backend. Then, examine the global and system configuration files. The http.sslbackend setting is the primary culprit here.

git config --list --show-origin | grep -i sslbackend
git --version

Use these commands to inspect your Git configuration and version. The --show-origin flag helps identify where a setting is defined.

Diagnostic Flow for SSL Backend Error

Resolving the Error: Step-by-Step Fixes

The solution typically involves reconfiguring Git to use a compatible SSL backend, usually OpenSSL, or ensuring that the schannel backend is correctly accessible if you intend to use it on Windows.

Option 1: Force OpenSSL Backend (Recommended for WSL and general cases)

This is the most common and effective solution, especially when working in WSL or if you prefer a consistent SSL backend across environments. It tells Git to explicitly use OpenSSL.

Option 2: Unset the SSL Backend Configuration

If you don't want to explicitly force OpenSSL, you can unset the http.sslbackend configuration. Git will then try to determine the best backend automatically, which usually defaults to OpenSSL on Linux-like systems.

Option 3: Reinstall Git (Windows Specific)

If you are on Windows and still encountering issues, a clean reinstall of Git for Windows can resolve corrupted installations or configuration issues. During installation, ensure you select the 'Use the OpenSSL library' option if prompted, or ensure 'Windows Secure Channel library' is correctly configured if you prefer schannel.

Option 4: Ensure ca-certificates is installed (WSL Specific)

On WSL, Git relies on the system's CA certificates for trust. Ensure they are up-to-date.

1. Step 1

Open your terminal (WSL terminal for WSL, Command Prompt/PowerShell for Windows).

2. Step 2

To force OpenSSL globally, run: git config --global http.sslbackend openssl.

3. Step 3

To unset the SSL backend configuration, run: git config --global --unset http.sslbackend.

4. Step 4

For WSL, update CA certificates with: sudo apt update && sudo apt install --reinstall ca-certificates.

5. Step 5

Test your Git connection by cloning a repository: git clone https://github.com/git/git.git.