Applying Custom Master Page using PowerShell or SPD in SharePoint 2013

Fixing Custom Master Page Issues using PowerShell and SPD in SharePoint 2013

sometime after deploying new branding WSP or customer master page, we encounter issues that few sites has been broken and getting 404 error message or Page not found.

As per my analysis there could be two reasons.

1. Master Page has not been publish/Functional 100% successfully, for this we can apply using PowerShell command.
   

   $web = Get-SPWeb http://mysite
   
   $web.CustomMasterUrl = "/_catalogs/masterpage/MyYogicustom.master"
   $web.MasterUrl = "/_catalogs/masterpage/MyYogicustom.master"
   
   $web.Update()

   Please note that CustomMasterURL is siteMaster Page and MasterURL is Master Page.
   MyYogicustom.master is master page name along with extention.
   
   
2. Sometime Site Pages masterpage directive not updated correct and its pointing to wrong or incorrect master page, for this open site page in SharePoint designer and update the master page value. Please check-In back page or else will not be visible to all users.