A webpage is not always broken because of a large mistake. Small details can produce exactly this problem: debugging: unexpected url resolution with base. This guide shows you what to look for, a concrete fix, and how to check that it worked.
The Idea in Plain English
A base href changes the meaning of relative URLs throughout the document, including some fragment links.
You can test this using a small local HTML file. Change one part at a time and check the result in the browser before adding more code.
A Working Example
The first part shows a problem. The second part shows a safer or more accurate version. Compare them before reading the explanation.
<!-- Problem -->
<base href="https://example.com/help/">
<a href="#topic">Jump to topic</a>
<!-- Corrected example -->
<base href="https://example.com/help/">
<a href="/help/lesson.html#topic">Jump to topic</a>
<h2 id="topic">Topic</h2>What Each Part Does
- The anchor is a link when its href points to a destination.
- The h2 identifies a major subsection.
- href is the URL or fragment destination of a link.
- id names an element for labels, fragments, CSS or JavaScript; IDs should be unique.
Before the fix, the browser can behave incorrectly or report a warning. After the change, test the exact failure rather than assuming the page is fixed.
Try It Yourself
Inspect the resolved URL and verify that it points to the intended document.
Common Beginner Mistakes
- Check the underlying cause before changing unrelated tags.
- Copying the code without checking whether its linked files or endpoints exist; sample addresses and file paths need real resources.
- Choosing a tag only because its default appearance looks right, without checking whether it describes the content correctly.
Key Takeaways
- A base href changes the meaning of relative URLs throughout the document, including some fragment links.
- Before the fix, the browser can behave incorrectly or report a warning. After the change, test the exact failure rather than assuming the page is fixed.
- Test the markup in a browser, and check accessibility and real-world behavior where relevant.