Site gets 404 error after upgrade to 2010

Question

I have a site collection with multiple sites. When I upgrade the site collection the sites all get 404. If i use Designer I can see the default.aspx file fine. If I rename it to default1.aspx then back to default.aspx the site is viewable from the browser.

I can always manually do this for all the subsites, but I would like to understand why this happens and what I can do to the 2007 site to prevent this.

Answer 1

Check-out the default.aspx and check-in back.

PowerShell script to do: http://salaudeen.blogspot.com/2011/02/404-page-not-found-error-after.html

Answer 2

This could be many things, a few suggestions:

1. Check ALL SharePoint features on your 2007 farm, install and activate on 2010 farm (it doesn't matter whether or not you plan on using them, sometimes a feature is getting in the way), if this works ascertain what each features is doing, if anyone is affecting default.aspx or the master pages, think about how to remediate this.
   
2. Try checking out and checking in the default.aspx file, version info may have been lost in transition
3. Remember this could be linked to everything linked to the default.aspx file, look at the master page, images, stylesheets, etc. verify everything is in place.

Failing that, start taking dives in the IIS and SharePoint logs. If you notice anything odd and likely related, feel free to post here.