About This HTML Issue
Every <img> element must include at least a src or a srcset attribute to be valid HTML.
The <img> element exists to embed an image into the document, and it needs to know where that image is. The src attribute provides a single URL for the image, while srcset lets you offer multiple image sources for different screen sizes or resolutions.
You might run into this error when using JavaScript to set the image source dynamically, or when using lazy-loading libraries that store the URL in a data- attribute like data-src. While those techniques work at runtime, they produce invalid HTML because the validator still expects src or srcset to be present in the markup.
If you genuinely don’t have a source yet, you can use a placeholder or a transparent pixel as the src value.
Invalid Example
<img alt="A cute cat" loading="lazy" data-src="cat.jpg">Valid Examples
Using src:
<img src="cat.jpg" alt="A cute cat">
Using srcset:
<img srcset="cat-400.jpg 400w, cat-800.jpg 800w"
sizes="(max-width: 600px) 400px, 800px"
alt="A cute cat">
Using both src and a lazy-loading data-src (keeps the markup valid while still supporting lazy loading):
<img src="placeholder.jpg" data-src="cat.jpg" alt="A cute cat">Find issues like this automatically
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