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HTML Guide

Free site validation

Find out what web pages on your sites are affected by HTML issues.

Bad value X for attribute “src” on element “iframe”: Illegal character in query: space is not allowed.

An <iframe> element allows to embed an HTML document inside another HTML document, and its src attribute is indicated the source URL of the embedded web page. The query part of that URL contains one or more space characters, which are not allowed, for example:

<iframe src=" 6th Avenue"></iframe>

You should properly escape all space characters as %20 like this:

<iframe src=""></iframe>

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Related W3C validator issues