Store owners may occasionally need to take their sites offline temporarily for maintenance, product updates, etc. This can easily by done by changing 2 keys in the web.config file. Taking the site down this way leaves the software running, but prevents customers from accessing it - they see instead whatever HTML page the store owner designs.
Setting up the Site Down For Maintenance Page
1 - Create a "Site Down For Maintenance" page. This must be in plain .htm file ONLY as *.html file will cause a redirect loop in version 9 software previous to MS 9.1.0.1
2 - Place the page you created in the web content folder (root).
3 - Go to the web.config file. Look for the following:
SiteDownForMaintenance and change its value to true.
SiteDownForMaintenancePage and change the value to the name of the page you have created.
4 - Save the file when you're done.
NOTE: If you are getting a redirect loop or error on a valid file, then verify the site Application Pool in IIS is set for Classic Managed Pipeline Mode, as Integrated Mode can cause this issue.