Issue with performing a database attach upgrade from 2007 to 2010. Apparently, when you have additional wildcard managed paths (anything other than '/sites') when you upgrade that database to SharePoint 2010 you will end up with a bunch of explicit managed paths in SharePoint 2010. Here’s how the whole thing looks 2007 Wildcard managed paths
2007 Site collections in content database
After attaching the content database to new SharePoint 2010 web application using the 'Mount-SPContentDatabase' PowerShell command, the managed paths section looks like follows
Clearly, the managed paths created are not the same as they were in 2007 and this is not a scenario we want to be in. For one when we try to create a new site collection named ‘upgrade’ under ‘IN’ we will not be able to create it at ‘/IN/upgrade’ since the managed path for ‘IN’ no longer exists.
Note All of your site collections will still be available in the above scenario.
Create managed paths before attaching 2007 content databases
Make a note of the managed paths you need before performing the upgrade and follow these steps
If you are already facing this issue, follow the steps listed below
that’s it folks!!