syntax of attribute value does not conform to declared value

Cause:

The value of an attribute contained something that is not allowed by the specified syntax for that type of attribute. For instance, the “selected” attribute must be either minimized as “selected” or spelled out in full as “selected="selected"”; the variant “selected=""” is not allowed.

Example:

textexample textexample

Bad:

textexample textexample

Good:

textexample textexample

Solution:

textexample textexample

References:

• W3 validator