Bad value X for attribute “width” on element “img”: Expected a digit but saw “"” instead.

A stray double quote ended up inside the width value of an <img>, usually because the opening quote is missing (width=200") or the quotes don't match (width='200"').

The width attribute takes a non-negative integer: digits only, with no quotes, units or spaces. Without an opening quote, the browser reads the value as unquoted, which runs until the next space or >, so the closing " becomes part of the value. The validator reports this case twice, once with this message and once as “"” in an unquoted attribute value. When the value opens with a single quote and closes with a double quote, it runs until the next single quote, and the " again lands inside it.

Browsers parse width leniently and read 200" as 200, so the image often looks fine. A value that starts with the quote, such as "200", fails to parse, and the browser ignores it. The image then gets no reserved space before it loads, and the content below it shifts once it arrives.

Templates and string-built HTML cause most of these, for example width=<%= width %>" with the opening quote left out. Put matching double quotes around the number.

Invalid example

<img src="photo.jpg" alt="A red car" width=200" height="150">
<img src="photo.jpg" alt="A red car" width='200"' height="150">

Valid example

<img src="photo.jpg" alt="A red car" width="200" height="150">

Learn more:

MDN Reference

MDN Web Docs: The image embed element

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WHATWG Spec

HTML Standard: Dimension attributes

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