Nginx中www域名跳转至根域名异常问题排查

Hey there, let's break down why this is happening—curl working but browsers showing the default Nginx page is a common gotcha, usually tied to caching or configuration priority. Here's what to check step by step:

1. Browser Cache is Almost Certainly the Culprit First #

301 redirects are permanently cached by browsers—even if you fixed your config later, your browser might still be clinging to an old response. Test this first:

• Open an incognito/private window and visit www.example.com—if it redirects correctly here, the issue is just your regular browser cache. Clear it (or use Ctrl+Shift+R to force a hard refresh) and you should be good.

2. Check Nginx Server Block Priority #

Nginx matches server blocks in the order they're listed in your config files. If your www.example.com redirect block comes after the default Nginx server block (the one with server_name _ or no explicit server_name), Nginx will hit the default block first and serve that page instead of redirecting.

• Fix this: Move your redirect server block to the top of your Nginx config (or the included config file) so it's the first block Nginx checks.

3. Double-Check Your Nginx Config is Applied #

Even if curl works, it's worth verifying you reloaded Nginx after making changes:

• Run sudo nginx -t to confirm your config has no syntax errors.
• Run sudo systemctl reload nginx to apply any changes (restarting works too, but reload is gentler).

4. Don't Forget HTTPS Configuration #

You mentioned HTTPS doesn't work for the redirect—browsers often default to HTTPS now, so if you don't have a server block handling www.example.com over port 443, Nginx will fall back to the default HTTPS block (or the default page if you don't have one set up).

• Add an HTTPS redirect block for www:

server {
    listen 443 ssl;
    server_name www.example.com;
    ssl_certificate /path/to/your/fullchain.pem;
    ssl_certificate_key /path/to/your/privkey.pem;
    return 301 $scheme://example.com$request_uri;
}

• Alternatively, if you use a tool like Certbot, it might have created a default HTTPS block that's catching these requests—make sure your www redirect block comes before that too.

5. Verify DNS (Just to Rule It Out) #

While curl working makes this unlikely, it's worth confirming your local DNS isn't pointing to an old IP:

• Run nslookup www.example.com or dig www.example.com on your local machine—ensure the IP matches your DigitalOcean Droplet.
• If it doesn't, flush your local DNS cache (Windows: ipconfig /flushdns, Mac: sudo dscacheutil -flushcache, Linux varies by distro).

Start with the browser cache and server block order—those are the most frequent fixes for this exact issue.

内容的提问来源于stack exchange，提问作者kidman01