Hey there, let's break down why your form isn't redirecting after submission on those older iPhone models and work through fixes step by step:

1. Add HTTP/HTTPS Protocol to URLs (Most Likely Culprit) #

Looking at your form code, the action and RETURN_URL values don't include a protocol (http:// or https://). Older iOS Safari versions (found on iPhone 6/6s/8, often running iOS 12 or earlier) treat URLs like www.abc.com as relative paths—meaning they try to navigate to [your-current-domain]/www.abc.com instead of the external site you intended.

Fix: Update your form attributes to include the full protocol:

<form name="online" id="form" action="https://www.abc.com" method="post" enctype="application/x-www-form-urlencoded" accept-charset="UTF-8">
  <input type="hidden" name="RETURN_URL" value="https://example.com/callback">
  <p class="edgeBox_Outer Adjust04">
    <input type="submit" id="submit" style="background: none;border: none;color:#fff;font-size: 90%;font-weight: bold; width:100%;cursor: pointer; touch-action: manipulation;" value ="Submit">
  </p>
</form>

2. Fix Button Interactivity for Old iOS Safari #

Your submit button has background: none and border: none, which might make old iOS Safari fail to recognize it as a fully interactive element. Here's a quick CSS adjustment to fix that:

• Add cursor: pointer to explicitly mark it as clickable
• Add touch-action: manipulation to eliminate browser touch delays that can block submission

If that still doesn't work, use a JavaScript fallback to manually trigger form submission:

document.getElementById('submit').addEventListener('click', function(e) {
  e.preventDefault();
  document.getElementById('form').submit();
});

3. Verify Form Encoding Compatibility #

While application/x-www-form-urlencoded is the default for POST forms, double-check that the target server (www.abc.com) explicitly supports this encoding. If needed, try removing the enctype attribute entirely to let the browser use its default value—this can resolve subtle compatibility issues with older WebKit engines.

Start with the protocol fix first—it's the most common issue for this scenario. If that doesn't resolve it, move on to the button interactivity tweaks.

内容的提问来源于stack exchange，提问作者Vijayarangan S