About This HTML Issue
A space before the width attribute value is causing the validator to misparse the iframe attributes, likely due to a missing closing quote on the width attribute.
This error typically occurs when there’s a typo in the attribute syntax, such as a missing closing quote or extra spaces inside the attribute value. The validator reads the raw HTML and interprets " height= as part of the width value because the width attribute’s opening quote was never properly closed.
The width and height attributes on an iframe element accept non-negative integer values representing pixels. Each attribute must have its value properly quoted and contain only digits.
HTML Examples
❌ Incorrect
<iframe src="page.html" width="600 height="400"></iframe>
In this example, the closing quote after 600 is missing. The validator sees the width value as 600 height=, which is not a valid number.
✅ Correct
<iframe src="page.html" width="600" height="400"></iframe>Each attribute has properly matched opening and closing quotes, and the values contain only digits.
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