How to fix fatal: Could not read from remote repository. Check that Pageant is running. in Git

First, verify whether Pageant is currently running:

1. Look in the system tray (bottom-right corner of Windows taskbar)
- Click the "^" arrow to show hidden icons
- Look for the Pageant icon (a computer with a hat)

2. Check via Task Manager:

Press Ctrl+Shift+Esc to open Task Manager
Look for "pageant.exe" in the list of processes

3. Check from command line:

# PowerShell
Get-Process pageant -ErrorAction SilentlyContinue

# Or Command Prompt
tasklist | findstr pageant

If Pageant is not running, proceed to start it. If it is running but you still see the error, your keys may not be loaded.

Start Pageant and add your SSH private key:

Start Pageant:
1. Open the Start menu and search for "Pageant"
2. Or navigate to your PuTTY installation folder and double-click pageant.exe
3. Pageant will appear in your system tray

Load your SSH key:
1. Right-click the Pageant icon in the system tray
2. Select "Add Key"
3. Navigate to your private key file (.ppk format)
4. Enter your passphrase if prompted
5. Click "Open"

Verify the key is loaded:
1. Right-click the Pageant icon
2. Select "View Keys"
3. Your key should appear in the list

Alternative - Load key from command line:

"C:\Program Files\PuTTY\pageant.exe" "C:\Users\YourName\.ssh\your_key.ppk"

Note: Pageant requires keys in PuTTY's .ppk format. If you have an OpenSSH key (like id_rsa or id_ed25519), you'll need to convert it first (see advanced notes).

To avoid this error after every restart, configure Pageant to start automatically with your keys:

Option 1: Add Pageant to Windows Startup

1. Press Win+R and type shell:startup
2. Create a shortcut to Pageant with your key as an argument
3. Right-click in the Startup folder > New > Shortcut
4. Enter the path:

"C:\Program Files\PuTTY\pageant.exe" "C:\Users\YourName\.ssh\your_key.ppk"

5. Name the shortcut "Pageant" and click Finish

Option 2: Create a batch file:

@echo off
start "" "C:\Program Files\PuTTY\pageant.exe" "C:\Users\YourName\.ssh\your_key.ppk"

Save as start-pageant.bat in your Startup folder.

Option 3: Use Task Scheduler
1. Open Task Scheduler
2. Create a new task to run at logon
3. Set the action to start Pageant with your key path

Note: If your key has a passphrase, you'll still be prompted to enter it when Pageant starts.

If you prefer to use Windows built-in OpenSSH instead of PuTTY tools, reconfigure Git:

Check current Git SSH configuration:

# Check GIT_SSH environment variable
echo %GIT_SSH%

# Or in PowerShell
$env:GIT_SSH

If this points to plink.exe, Git is using PuTTY.

Remove the GIT_SSH setting:

# Remove from current session
set GIT_SSH=

# Remove permanently (System Properties > Environment Variables)
# Or via PowerShell (run as Administrator)
[Environment]::SetEnvironmentVariable("GIT_SSH", $null, "User")

Configure Git to use OpenSSH:

# Set Git to use Windows OpenSSH
git config --global core.sshCommand "C:/Windows/System32/OpenSSH/ssh.exe"

# Or for Git Bash's built-in SSH
git config --global core.sshCommand "ssh"

Verify the change:

git config --global core.sshCommand

After this change, Git will use OpenSSH instead of PuTTY, and you won't need Pageant.

If you switched to OpenSSH, set up SSH authentication:

Start the OpenSSH Authentication Agent:

# Check if service is running (run PowerShell as Administrator)
Get-Service ssh-agent

# Set to start automatically
Set-Service -Name ssh-agent -StartupType Automatic

# Start the service
Start-Service ssh-agent

Generate or use existing SSH keys:

# Generate a new key (if needed)
ssh-keygen -t ed25519 -C "your_email@example.com"

# Add your key to the agent
ssh-add ~/.ssh/id_ed25519

Test the connection:

ssh -T git@github.com

You should see: "Hi username! You've successfully authenticated..."

If you have an existing PuTTY key (.ppk):

You'll need to convert it to OpenSSH format using PuTTYgen:
1. Open PuTTYgen
2. Click "Load" and select your .ppk file
3. Go to Conversions > Export OpenSSH key
4. Save as ~/.ssh/id_rsa or similar
5. Add to ssh-agent with ssh-add

Confirm Git is using the correct SSH method:

Check all SSH-related settings:

# Check core.sshCommand
git config --global core.sshCommand

# Check GIT_SSH environment variable
echo %GIT_SSH%

# List all SSH-related config
git config --list | findstr -i ssh

Test Git SSH access:

# Use GIT_TRACE for detailed debugging
set GIT_TRACE=1
git ls-remote git@github.com:username/repo.git

# Or with SSH debugging
set GIT_SSH_COMMAND=ssh -vvv
git ls-remote git@github.com:username/repo.git

Expected behavior:
- If using Pageant: Git should use plink.exe and require Pageant running
- If using OpenSSH: Git should use Windows ssh.exe and use ssh-agent

Verify which SSH is being used:

# In Git Bash
which ssh

# Should show:
# /usr/bin/ssh (Git Bash's OpenSSH)
# or
# /c/Windows/System32/OpenSSH/ssh (Windows OpenSSH)

If Pageant is running with keys loaded but Git still can't connect:

Verify plink can reach Pageant:

# Test with plink directly
plink -v git@github.com

Look for messages about Pageant in the output.

Check if running as different user:

Pageant only serves keys to processes running as the same Windows user. If you:
- Run Git as Administrator but Pageant as regular user
- Use a service account for builds
- Run in a different Remote Desktop session

The processes cannot share Pageant's keys.

Solutions:
1. Run Git in the same user context as Pageant
2. For services, use the Windows Credential Manager or deploy keys
3. For CI/CD, use OpenSSH with key files instead of Pageant

Antivirus/Security software interference:

Some security software blocks inter-process communication:
1. Temporarily disable antivirus
2. Check if Pageant is whitelisted
3. Look for blocked connections in security logs

Restart Pageant:

# Kill and restart Pageant
taskkill /F /IM pageant.exe
"C:\Program Files\PuTTY\pageant.exe" "C:\path\to\your\key.ppk"