t6_mem0/FIX_502_ERROR.md

Fix 502 Error for docs.klas.chat

🔍 Root Cause Analysis

The 502 error on docs.klas.chat is caused by two issues:

1. Caddyfile Syntax Error: Line 276 has incorrect indentation
2. Mintlify Server Not Running: The target port is not bound

🛠️ Issue 1: Fix Caddyfile Syntax Error

Problem: Line 276 in /etc/caddy/Caddyfile has incorrect indentation:

  encode gzip  # ❌ Wrong - uses spaces

Solution: Fix the indentation to use a TAB character:

sudo nano /etc/caddy/Caddyfile

Change line 276 from:

  encode gzip

to:

	encode gzip

(Use TAB character for indentation, not spaces)

🚀 Issue 2: Start Mintlify Server

Problem: No service is running on the target port.

Solution: Start Mintlify on a free port:

Option A: Use Port 3005 (Recommended)

1. Update Caddyfile to use port 3005:

   sudo nano /etc/caddy/Caddyfile
   

   Change line 275 from:

   reverse_proxy localhost:3003
   

   to:

   reverse_proxy localhost:3005
   

2. Start Mintlify on port 3005:

   cd /home/klas/mem0/docs
   mint dev --port 3005
   

3. Reload Caddy:

   sudo systemctl reload caddy
   

Option B: Use Port 3010 (Alternative)

If port 3005 is also occupied:

1. Update Caddyfile to use port 3010
2. Start Mintlify:

   cd /home/klas/mem0/docs
   mint dev --port 3010
   

📋 Complete Fix Process

Here's the complete step-by-step process:

Step 1: Fix Caddyfile Syntax

# Open Caddyfile in editor
sudo nano /etc/caddy/Caddyfile

# Find the docs.klas.chat section (around line 267)
# Fix line 276: change "  encode gzip" to "	encode gzip" (use TAB)
# Change line 275: "reverse_proxy localhost:3003" to "reverse_proxy localhost:3005"

Corrected docs.klas.chat section should look like:

docs.klas.chat {
	tls /certs/klas.chat/fullchain.cer /certs/klas.chat/klas.chat.key

	# Basic Authentication
	basicauth * {
		langmem $2a$14$.1fx02QwkkmfezhZMLE4Iu2N/ub5vwDSAtcH9lAa5z11ChjiYy1PG
	}

	reverse_proxy localhost:3005
	encode gzip
}

Step 2: Validate and Reload Caddy

# Validate Caddyfile syntax
sudo caddy validate --config /etc/caddy/Caddyfile

# If validation passes, reload Caddy
sudo systemctl reload caddy

Step 3: Start Mintlify Server

cd /home/klas/mem0/docs
mint dev --port 3005

Step 4: Test the Fix

# Test direct connection to Mintlify
curl -I localhost:3005

# Test through Caddy proxy (should work after authentication)
curl -I -k https://docs.klas.chat

🔍 Port Usage Analysis

Current occupied ports in the 3000 range:

• 3000: Next.js server (PID 394563)
• 3001: Unknown service
• 3002: Unknown service
• 3003: Not actually bound (Mintlify failed to start)
• 3005: Available ✅

🆘 Troubleshooting

If Mintlify Won't Start

# Check for Node.js issues
node --version
npm --version

# Update Mintlify if needed
npm update -g mint

# Try a different port
mint dev --port 3010

If Caddy Won't Reload

# Check Caddy status
sudo systemctl status caddy

# Check Caddy logs
sudo journalctl -u caddy -f

# Validate configuration
sudo caddy validate --config /etc/caddy/Caddyfile

If 502 Error Persists

# Check if target port is responding
ss -tlnp | grep 3005

# Test direct connection
curl localhost:3005

# Check Caddy is forwarding correctly
curl -H "Host: docs.klas.chat" http://localhost:3005

✅ Success Criteria

After applying the fixes, you should see:

1. Caddy validation passes: No syntax errors
2. Mintlify responds: curl localhost:3005 returns HTTP 200
3. docs.klas.chat loads: No 502 error, shows documentation
4. Authentication works: Basic auth prompt appears

🔄 Background Service (Optional)

To keep Mintlify running permanently:

# Create systemd service
sudo nano /etc/systemd/system/mem0-docs.service

[Unit]
Description=Mem0 Documentation Server
After=network.target

[Service]
Type=simple
User=klas
WorkingDirectory=/home/klas/mem0/docs
ExecStart=/usr/local/bin/mint dev --port 3005
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target

# Enable and start service
sudo systemctl enable mem0-docs
sudo systemctl start mem0-docs

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Summary: Fix the Caddyfile indentation error, change the port to 3005, and start Mintlify on the correct port.