Encountered this error HTTP 403: The Website declined to Show this webpage on the SharePoint Site Collection while doing some maintenance work
This error (HTTP 403 Forbidden) means that Internet Explorer was able to connect to the website, but it does not have permissions to view the webpage
The error itself says the browser was able to connect but doesn’t seem to have permissions. In 2007 version, before taking backup’s site collections were set to read only so it doesn’t interrupt backup process or there are commands to lock the site with no access , read only etc.
You can find this by executing the getsitelock command
stsadm -o getsitelock -url http://portal.contoso.com/
Result was noaccess that says no one not even Site Collection Administrator or nor Farm account can access the same
stsadm -o setsitelock -url http://portal.contoso.com/ -lock none
Other attributes that are available are none | noadditions | readonly | noaccess
ULS logs are not helpful as it should be at times and it’s frustrating to see this, no Info in ULS logs that the site is locked with no access.