Enable Custom Master Pages on SharePoint 2010

The Problem:

You have created a custom master page.  It looks great.

Now, how do you apply it to the Site Collection and all of the Subsites?

*** If you already have a Site Collection with the custom Master Page enabled, and have added a new Subsite that isn't inheriting, please skip to Subsite.

Site Collection:

We need to verify that the master page you wish to enable, is published and approved by visiting:

http://[SharePoint2010SiteCollection]/_catalogs/MasterPage/Forms/AllItems.aspx

Here, you should see a list of all of the master pages and branding pages that are available on the Site Collection, including the out-of-the-box master pages included with SharePoint 2010.

To verify this file is published and approved, make sure it is present in this list, and shows an 'Approval Status' of Approved.  If you need to publish a master page, simply check the page in.

Once we have verified the master page, we need to visit the Change Site Master Page form here:

http://[SharePoint2010SiteCollection]/_layouts/ChangeSiteMasterPage.aspx

Here, you will find the Site Master Page Settings, which includes the Site Master Page and System Master Page selections.  After selecting the option to 'Specify a master page to be used by this site and all sites that inherit from it', you should be able to find your custom master page in the dropdown.  After changing both the System and Site master pages, click 'OK' to apply the changes.

Subsite:

Now that your custom master page is activated on your Site Collection, you may have some issues when creating new subsites.  The master page seems to revert back to the default SharePoint 2010 master page.

In order to fix this, we will visit the Change Site Master Page again, this time on the subsite level:

http://[SharePoint2010SiteCollection]/[subsite]/_layouts/ChangeSiteMasterPage.aspx

Here you will find the same options as you saw on the Site Collection change page.  We will follow the same steps again:

• Select the option to 'Specify a master page to be used by this site and all sites that inherit from it' 
• Your custom master page should be available in the dropdown.  
• After changing both the System and Site master pages, click 'OK' to apply the changes.

linkback: http://stackoverflow.com/questions/3532367/sharepoint-2010-how-to-apply-custom-master-page-and-theme-to-all-subsites