Message
foo must be an W3CDTF date
Explanation
Invalid date.
Solution
The value specified must adhere to the W3C Date and Time Format, which is a profile of ISO 8601.
An example of a valid W3CDTF Date: 2002-10-02T10:00:00-05:00
Not clear? Disagree?
You might be able to find help in one of these fine resources.
