SharePoint Designer 2010 Can't open Page Layout in Edit Mode

Question

Every time I try to open any page layout in my site collection SharePoint Designer 2010 throws the the following error at me.

Can't figure out what's wrong. I've used it fine with other site collections before.

Any ideas?

Answer 1

I have since found out what caused this issue.

I was missing the following handler for asmx within my web.config file

      <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />

Answer 2

when opening your site collection, try to specify the full name for this collection. for example, instead of http://localhost , try something like this: http://fullname.domain.com

Or, probably a better way to fix it: go to Central Administration ( /_admin/AlternateUrlCollections.aspx) and check your alternative access names. When you open your collection in Designer you have to use exactly the same URLs.