Resolution for TEMPLATE ERROR: Invalid data reference post.url: No dictionary named: 'post' in: ['blog']

Problem 

Widget doesn't display correctly and display following message on the blog

TEMPLATE ERROR: Invalid data reference post.url: No dictionary named: 'post' in: ['blog']

Cause 

That error usually occurs when you place the code outside of Blog widget. Sometime the widget asks you to place the code below 

<b:includable id='post' var='post'>

but you couldn't find the code and hence placed the code somewhere else.

Resolution 

Step 1 - At Template -> Edit HTML 

Check Expand Widget Templates

Step 2 - Ctrl + f and find the code <b:includable id='post' var='post'>


Step 3 - Cut the code from previous location and Paste it below <b:includable id='post' var='post'>.