Master Page issue : The base type is not allowed for this page. The type is not registered as safe

Hi,

Ever faced a scenario where you edited a SharePoint master page with SharePoint designer and suddenly the whole site is down with an error message

The base type is not allowed for this page. The type is not registered as safe

Well, recently i faced the same issue and fortunately there is help out there to fix and bring everything to normal. Solution is to re ghost the master page or in other words reset to site definition.

  1. Navigate to Site Settings.
  2. Under Look and feel find and navigate to Reset to site definition, and as the url suggests(_layouts/15/reghost.aspx).
  3. Paste the URL of the master page, from the master page gallery.
  4. Click reset to confirm.

Once done, the error should be gone and you site should be back up.