If you are trying to figure out why Coolite/ExtJs is giving an error while loading DateTime you serialized to Json manually (including serialization to json of records which contain Datetime fields), here is the answer.

Well, as far as I have seen, Coolite/ExtJs components (including the store) only accept one serialization format for DateTime fields, that is the sortable date/time pattern that conforms to ISO 8601 pattern.

The custom format string for this pattern in .NET that can be passed to the DateTime ToString() method is:

Alternatively, you can also use the standard DateTime format specifier for this format, which is “s” in for the DateTime’s ToString() method.

Sortable date/time pattern; conforms to ISO 8601