I'm having issues with the SharePoint 2013 Design Manager. I have created a new content type that inherits from the "Article Page" content type. I add two custom columns and then created a new page layout in the design manager based on the new content type. The new page layout sucessfully created with message "Conversion successful".
Then I click the html file. Everything seems fine beside when I click the "Snippet" link button at right top corner. I get the error "Sorry, something went wrong An unexpected error has occurred". After checked through the ULS log it is not useful.
Application error when access /_layouts/15/ComponentConfigureControls.aspx, Error=Object reference not set to an instance of an object.
What could be wrong?