Open in Notepad:
First, change customErrors mode in "Off"
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Second, change CallStack="true"
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Refresh the page with error
For example, if you have a Web application named http://sharepoint.com and you want to add a host-named site collection with the URL http://about.sharepoint.com, use the following command:
stsadm -o renamesite -oldUrl http://www.name.com -newUrl http://www.newname.com