Sharepoint Site master page not applied using designer

Question

I have converted my HTML to masterpage and published a major version of it. When applying master page using design master page, I change the site master page to my newly converted masterpage and the system master page to seattle.

However the master page does not get applied to site. When changing the system mp to custom mp the mp gets applied. This also changes the layout of the admin pages(like site settings, contents,etc).

I do not want to apply my master page to site admin pages. Kindly help!

Answer 1

The distinction between the system master page (aka "default master page" in SharePoint Designer, aka MasterUrl in the C# API) and the site master page (aka "custom master page" in SharePoint Designer, aka CustomMasterUrl in the C# API) only appears for publishing sites.

In a team site, only the system master page is taken into account for both the site pages (i.e. the wiki pages relying in the SitePages doc lib) and the "admin" pages (the ones in the _layouts virtual folder).

In a publishing site, publishing pages (the ones from the Pages library) do use the site master page. All other pages (wiki pages, if any, and _layouts pages) still use the system MP.