Customize Post.aspx Without Error

In order to customize SharePoint blog's Post.aspx page, you need to convert it into XSLT Data View using SharePoint designer. But, the problem is when you try to convert it, the below error occurs:

"Failed setting processor stylesheet: Expression expected. -->=<--@Author"


Solution:

1. In your SharePoint blog site, go to Post.aspx.
2. Click Site Actions >> Edit Page
3. Delete Post webpart
4. Add new Post webpart.
5. Exit edit mode.
6. Open Post.aspx using Sharepoint Designer
7. Right-click Post webpart and then convert to XSLT Data View. (You should now be able to convert it without error)
8. In Common Data View Tasks >> Parameters >> add new parameter ID (Parameter source = Query String; Query String Variable = ID)
9. In Common Data View Tasks >> Filter >> add filter ID Equals [ID]. 

After that, you can now edit the default display page of a SharePoint blog site based on your requirements.