"Why Posted Date is Displayed as 'Undefined' in my Blogger blog?", This is a very popular question asking from us every day in comments and using contact form.
When you upload a new blogger template to your blog which has a custom post timestamp display, you will see posted dates of blog posts showing as "undefined" or not showing.
Many users think, it is an error of that Blogger theme. But this is not a error in the template, to fix this problem you need to change "Timestamp Format" of your Blogger blog.
You need to go "Settings" --> "Language and formatting" of your blog.
Select "Timestamp Format" from drop-down menu similar to "Sunday, June 15, 2014" format.
Important: You need to change "Timestamp Format". Not "Comment Timestamp Format".
Click on "Save settings" button and you are done.