Great question! The initial HTTP/1.1 request you're seeing ties back to how HTTP/2 can be negotiated—either via the Upgrade header (which requires that initial HTTP/1.1 request) or ALPN (Application Layer Protocol Negotiation) during the TLS handshake. To skip the upgrade step entirely, we need to make sure your setup leverages ALPN correctly. Here's how to fix it:

1. Fix Your AWS Server's ALPN Configuration #

This is the most critical step. If your server doesn't support ALPN (or doesn't prioritize HTTP/2), React Native's underlying iOS network stack (NSURLSession) can't negotiate HTTP/2 during the TLS handshake, forcing it to use the upgrade path instead.

• For AWS ALB: Ensure you're using a TLS policy that includes HTTP/2 support (like ELBSecurityPolicy-TLS-1-2-2017-01 or newer) and that HTTP/2 is enabled for the load balancer. The ALB will automatically handle ALPN negotiation with h2 as the priority.
• For self-managed servers (e.g., Nginx on EC2): Add these lines to your SSL configuration to enable ALPN and prioritize HTTP/2:

  ssl_protocols TLSv1.2 TLSv1.3;
  ssl_alpn_protocols h2 http/1.1;
  ssl_prefer_server_ciphers on;
  

• Verify your server's ALPN support with this curl command:

  curl --http2 -v https://your-server-domain.com
  

  Look for lines like ALPN, offering h2 and ALPN, server accepted to use h2 to confirm ALPN is working correctly.

2. Ensure React Native iOS Network Stack is Configured for HTTP/2 #

React Native relies on iOS's NSURLSession for network requests, which natively supports HTTP/2 when ALPN is available. But you need to make sure your app's ATS (App Transport Security) settings don't block this:

• Update your Info.plist to enforce TLS 1.2+ (required for HTTP/2) and allow your server's domain:

  <key>NSAppTransportSecurity</key>
  <dict>
      <key>NSAllowsArbitraryLoads</key>
      <false/>
      <key>NSExceptionDomains</key>
      <dict>
          <key>your-server-domain.com</key>
          <dict>
              <key>NSIncludesSubdomains</key>
              <true/>
              <key>NSTemporaryExceptionMinimumTLSVersion</key>
              <string>TLSv1.2</string>
          </dict>
      </dict>
  </dict>
  

  Avoid disabling ATS entirely unless necessary—stick to domain-specific exceptions for better security.

3. Check Axios/Fetch Configurations #

Neither Axios nor Fetch should force HTTP/1.1 by default, but it's worth confirming your setup isn't overriding this behavior:

• Axios: React Native's Axios uses the built-in XMLHttpRequest (which wraps NSURLSession). No special configuration is needed, but if you've customized the adapter, ensure it doesn't disable HTTP/2 support. Avoid setting headers that explicitly force HTTP/1.1 (like unnecessary Connection: keep-alive overrides).
• Fetch: Fetch in React Native iOS is also backed by NSURLSession, so it will automatically use HTTP/2 if ALPN is negotiated correctly. No extra setup is required here.

4. Troubleshooting Common Issues #

• If you still see the initial HTTP/1.1 request: Double-check your server's TLS certificate is valid and trusted by iOS (use a public CA like Let's Encrypt, or add your custom cert to the app's trust store). Invalid certs can cause NSURLSession to fall back to HTTP/1.1.
• Test with a native iOS app: Create a simple Swift app using URLSession to hit your server—if it connects directly over HTTP/2, the issue may be in an older React Native version. Consider upgrading to the latest stable release to fix any network layer bugs.

Summary #

The key to skipping the initial HTTP/1.1 request is enabling ALPN on your AWS server and prioritizing HTTP/2 during the TLS handshake. Once that's set up, React Native's iOS network stack will negotiate HTTP/2 directly without needing the upgrade step.

内容的提问来源于stack exchange，提问作者Amal