# 🔧 Troubleshooting Guide for 404 and 502 Errors

## Quick Diagnosis

Run these commands on your Ubuntu server to diagnose the issue:

```bash
# 1. Check if files exist
ls -la /var/www/dexarmarket/browser/index.html

# 2. Check nginx config syntax
sudo nginx -t

# 3. Check nginx error logs (THIS IS MOST IMPORTANT!)
sudo tail -30 /var/log/nginx/error.log

# 4. Check if nginx is running
sudo systemctl status nginx

# 5. Test API from server
curl -v https://api.dexarmarket.ru:445/ping
```

## Error: 404 Not Found

### Cause: Files not uploaded or wrong path

**Solution 1: Verify files are on server**
```bash
ls -la /var/www/dexarmarket/browser/
```

Should show:
- `index.html`
- `main-*.js`
- `chunk-*.js`
- `polyfills-*.js`
- `styles-*.css`
- `assets/` folder

**If files are missing:**
```bash
# From your local machine:
cd F:\dx\marketplace\Dexarmarket
npm run build
scp -r dist/dexarmarket/browser/* user@your-server:/var/www/dexarmarket/browser/
```

**Solution 2: Fix permissions**
```bash
sudo chown -R www-data:www-data /var/www/dexarmarket
sudo chmod -R 755 /var/www/dexarmarket
```

**Solution 3: Check nginx config is loaded**
```bash
# Check which config is active
ls -la /etc/nginx/sites-enabled/

# Should show symlink to dexarmarket config
# If not:
sudo ln -s /etc/nginx/sites-available/dexarmarket /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx
```

**Solution 4: Verify nginx root path**
```bash
sudo cat /etc/nginx/sites-available/dexarmarket | grep root
```

Should show: `root /var/www/dexarmarket/browser;`

## Error: 502 Bad Gateway

### This means the API backend (https://api.dexarmarket.ru:445) is unreachable

**Solution 1: Check if API is running**
```bash
# From Ubuntu server:
curl -v https://api.dexarmarket.ru:445/ping

# If this fails, your API backend is down!
```

**Solution 2: Port 445 is blocked**
Port 445 is typically blocked by many firewalls because it's used for SMB file sharing.

**Check from browser console (F12):**
- Open browser Developer Tools (F12)
- Go to Console tab
- Look for errors like: `net::ERR_CONNECTION_REFUSED` or `net::ERR_SSL_PROTOCOL_ERROR`

**Possible fixes:**
- Use standard port 443 for HTTPS
- Or use port 8443, 8080, or other non-standard but common ports
- Configure firewall to allow port 445

**Solution 3: CORS issues**
The API must have CORS headers allowing requests from `https://dexarmarket.ru`

Check API response headers:
```bash
curl -v -H "Origin: https://dexarmarket.ru" https://api.dexarmarket.ru:445/ping
```

Should include headers like:
```
Access-Control-Allow-Origin: https://dexarmarket.ru
```

**Solution 4: SSL Certificate issues**
```bash
# Test with SSL verification disabled
curl -k https://api.dexarmarket.ru:445/ping

# If this works but normal curl doesn't, SSL cert is invalid
```

## Still Not Working?

### Get detailed error information:

**1. Browser Console (JavaScript errors)**
```
F12 → Console tab
Look for red errors
```

**2. Browser Network Tab (Failed requests)**
```
F12 → Network tab
Reload page
Look for red (failed) requests
Click on failed request to see details
```

**3. Nginx Error Log (Server-side errors)**
```bash
sudo tail -50 /var/log/nginx/error.log
```

**4. Nginx Access Log (See what requests come in)**
```bash
sudo tail -50 /var/log/nginx/access.log
```

**5. Test Build Locally**
```bash
cd F:\dx\marketplace\Dexarmarket\dist\dexarmarket\browser
python -m http.server 8000
# Visit http://localhost:8000
```

If local test works, the issue is with deployment, not the build.

## Common Mistakes

❌ **Uploading to wrong directory**
- Correct: `/var/www/dexarmarket/browser/`
- Wrong: `/var/www/dexarmarket/` (missing browser/)

❌ **Wrong permissions**
```bash
# Must be readable by www-data
sudo chown -R www-data:www-data /var/www/dexarmarket
sudo chmod -R 755 /var/www/dexarmarket
```

❌ **Nginx config not reloaded**
```bash
# After ANY change to nginx config:
sudo nginx -t
sudo systemctl reload nginx
```

❌ **Old files cached**
```bash
# Clear browser cache: Ctrl+Shift+R (hard refresh)
```

❌ **API port blocked**
- Port 445 is unusual and often blocked
- Consider using port 443 (standard HTTPS)

## Contact Information for Support

When asking for help, provide:
1. Output of `sudo nginx -t`
2. Last 30 lines of nginx error log: `sudo tail -30 /var/log/nginx/error.log`
3. Browser console errors (F12 → Console)
4. Result of `curl -v https://api.dexarmarket.ru:445/ping` from server
5. Screenshot of browser Network tab showing failed request