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:
```bash
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:
   ```bash
   sudo nano /etc/caddy/Caddyfile
   ```
   
   Change line 275 from:
   ```
   reverse_proxy localhost:3003
   ```
   to:
   ```
   reverse_proxy localhost:3005
   ```

2. **Start Mintlify on port 3005**:
   ```bash
   cd /home/klas/mem0/docs
   mint dev --port 3005
   ```

3. **Reload Caddy**:
   ```bash
   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**:
   ```bash
   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
```bash
# 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
```bash
# Validate Caddyfile syntax
sudo caddy validate --config /etc/caddy/Caddyfile

# If validation passes, reload Caddy
sudo systemctl reload caddy
```

### Step 3: Start Mintlify Server
```bash
cd /home/klas/mem0/docs
mint dev --port 3005
```

### Step 4: Test the Fix
```bash
# 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
```bash
# 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
```bash
# 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
```bash
# 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:

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

```ini
[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
```

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

---

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