Title: w3 validator problem in plugin
Last modified: August 21, 2016

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# w3 validator problem in plugin

 *  [gunlerden](https://wordpress.org/support/users/gunlerden/)
 * (@gunlerden)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/w3-validator-problem-in-plugin/)
 * hello,
 * This is a nice add-on
 * but
 * there are errors in w3!. Please help!
 * Error Code:
 * > …3.org/1999/xhtml” lang=”en-US” prefix=”og: [http://ogp.me/ns#”><head](http://ogp.me/ns#”><head)
   > profile=”h…
   > ✉
   > You have used the attribute named above in your document, but the document 
   > type you are using does not support that attribute for this element. This error
   > is often caused by incorrect use of the “Strict” document type with a document
   > that uses frames (e.g. you must use the “Transitional” document type to get
   > the “target” attribute), or by using vendor proprietary extensions such as “
   > marginheight” (this is usually fixed by using CSS to achieve the desired effect
   > instead).
   > This error may also result if the element itself is not supported in the document
   > type you are using, as an undefined element will have no supported attributes;
   > in this case, see the element-undefined error message for further information.
 * >  Line 1, Column 999: there is no attribute “property”
   > …/www.hack-free.com/” /><meta property=’og:locale’ content=’en_US’/><meta prope…
   > ✉
   > You have used the attribute named above in your document, but the document 
   > type you are using does not support that attribute for this element. This error
   > is often caused by incorrect use of the “Strict” document type with a document
   > that uses frames (e.g. you must use the “Transitional” document type to get
   > the “target” attribute), or by using vendor proprietary extensions such as “
   > marginheight” (this is usually fixed by using CSS to achieve the desired effect
   > instead).
   > This error may also result if the element itself is not supported in the document
   > type you are using, as an undefined element will have no supported attributes;
   > in this case, see the element-undefined error message for further information.
 * [http://wordpress.org/extend/plugins/wordpress-seo/](http://wordpress.org/extend/plugins/wordpress-seo/)

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 * 0 replies
 * 1 participant
 * Last reply from: [gunlerden](https://wordpress.org/support/users/gunlerden/)
 * Last activity: [13 years, 1 month ago](https://wordpress.org/support/topic/w3-validator-problem-in-plugin/)
 * Status: not resolved