After successfully upgrading this blog's engine - the BlogEngine.NET from version 1.3 to version 1.4.5, I thought I have enough to help you with the upgrade and hence this post is here. But, as I use XML provider, I won't be able to guide on the MSSQL or any other supported database/provider setup. So, if you also use XML data store, here are the steps in brief to upgrade from BlogEngine.NET 1.3 to BlogEngine.NET 1.4.5 -

Backup

This is the most important step as only a backup can save you from any unexpected issues in the upgrade process. Though you can live with only App_Data folder, Extensions (if you have custom extensions installed), Themes (if you have customized one) and custom images/pics, yet I would insist you to take a full backup so that you can get back to previous state anytime.

Download BlogEngine.NET 1.4.5

Download the build from http://www.codeplex.com/blogengine/Release/ProjectReleases.aspx

Prepare the Upgrade

• Extract the BlogEngine.NET 1.4.5 files to a directory.
• Copy data and other files from backup to the new build.
  • Copy all Posts, Pages, Blogroll and Categories xml.
  • If you have any other customizations, such as PingServices, copy that as well.
  • Copy Extensions and required files (dlls, images) to appropriate folderso   Copy customized Themes.
• Don't copy users, roles and settings files; that is for later.

Local Setup

If you are an advanced user and have some customizations running on BlogEngine.NET, I would highly recommend this step as it would ensure everything is in place before we publish it to the world.

Configure the upgrade folder as a virtual directory in local IIS (if you don't understand what this is, please skip this step).

Test the blog on local IIS. If everything looks good you are almost ready to go, otherwise tweak your customizations to fit the new build.

• Configure Users 
  • Don’t copy Users.xml file for the reason that prior to 1.4 version password encryption was not supported.
  • Login to administration using default Admin login.
  • Create a user for yourself.
  • Logout and test the new user login.
  • Remove the default admin login.
• Now configure Settings
  • Best method is to use the administration screen and re-enter all settings.
  • In case you have forgotten some value, refer to the Settings.xml in your backup.
• If you want, configure widgets and the look and feel of your blog.

No-local setup?

If you have skipped 'Local Setup' step, this step is for you.

• Configure Users
  • Open Users.xml and set the password to blank
    example - <Password></Password>
  • Now you can use the default password 'admin' to login.
• Carefully copy settings, one by one, from old Settings.xml to new Settings.xml. Copy only values, if any node is not there in the new file, ignore it and don't copy that node.

Publish the upgrade

• Delete all files and folders from existing blog.
• Upload the upgrade to your blog

That's it!