I get a similar error using the latest uBlogsy available through the package manager and Umbraco 4.8 of:

Blog Import tool

Blog import failed :( 
Please report issues here with the stacktrace below.

Object reference not set to an instance of an object.

StackTrace:
at uBlogsy.BusinessLogic.DocumentService.GetDocumentByAlias(Document current, String rootAlias, String alias) in D:\_PROJECTS\Personal\uBlogsy - Blog\Branches\2.1.0.0\uBlogsy\uBlogsy.BusinessLogic\DocumentService.cs:line 142 at uBlogsy.Web.usercontrols.uBlogsy.dashboard.RSSImport.Import() in D:\_PROJECTS\Personal\uBlogsy - Blog\Branches\2.1.0.0\uBlogsy\uBlogsy\usercontrols\uBlogsy\dashboard\RSSImport.ascx.cs:line 60 at uBlogsy.Web.usercontrols.uBlogsy.dashboard.RSSImport.btnRssImport_Click(Object sender, EventArgs e) in D:\_PROJECTS\Personal\uBlogsy - Blog\Branches\2.1.0.0\uBlogsy\uBlogsy\usercontrols\uBlogsy\dashboard\RSSImport.ascx.cs:line 31

I see that a folder of D:\_Projects is in the error?

Same story here with Umbraco 4.7.2 and latest uBlogsy 2.1.1.0:

Was about to import http://feeds.feedburner.com/midcodecrisis for testing and got same error:

Object reference not set to an instance of an object.

StackTrace:
 at uBlogsy.BusinessLogic.DocumentService.GetDocumentByAlias(Document current, String rootAlias, String alias) in D:\_PROJECTS\Personal\uBlogsy\Branches\2.1.1.0\uBlogsy\uBlogsy.BusinessLogic\DocumentService.cs:line 142 at uBlogsy.Web.usercontrols.uBlogsy.dashboard.RSSImport.Import() in D:\_PROJECTS\Personal\uBlogsy\Branches\2.1.1.0\uBlogsy\uBlogsy\usercontrols\uBlogsy\dashboard\RSSImport.ascx.cs:line 60 at uBlogsy.Web.usercontrols.uBlogsy.dashboard.RSSImport.btnRssImport_Click(Object sender, EventArgs e) in D:\_PROJECTS\Personal\uBlogsy\Branches\2.1.1.0\uBlogsy\uBlogsy\usercontrols\uBlogsy\dashboard\RSSImport.ascx.cs:line 31

Did you resolve this issue?

Can you paste your content tree?

Hi Anthony,

The problem is not resolved.
By "content tree" do you mean umbraco.config xml? It's 5k lines...

Just take a screen grab of your content tree and paste it.

is working on a reply...