I had made a couple of changes to a site which I believe caused this issue. The symptom is, click on 'View all site content' on a subsite and it will show the view all site content page of the root site. I made some changes to the master page:
<td class="s4-titlelogo"> <SharePoint:SPLinkButton runat="server" NavigateUrl="/" id="onetidProjectPropertyTitleGraphic"> <SharePoint:SiteLogoImage name="onetidHeadbnnr0" id="onetidHeadbnnr2" LogoImageUrl="/_layouts/images/siteIcon.png" runat="server"/> </SharePoint:SPLinkButton> </td> <td class="s4-titletext"> <h1 name="onetidProjectPropertyTitle"> <asp:ContentPlaceHolder id="PlaceHolderSiteName" runat="server"> <SharePoint:SPLinkButton runat="server" NavigateUrl="/" id="onetidProjectPropertyTitle"><SharePoint:ProjectProperty Property="Title" runat="server" /></SharePoint:SPLinkButton> </asp:ContentPlaceHolder> </h1>
with the NavigateURL set to "/" for the titlelogo and titletext. I realised I probably only wanted it to be the titlelogo and applied the master page and reset subsites to use it.
I subsequently changed the masterpage page but problem exists. As a side thing we changed the default AAMs for the site so that was the other change made.
When I try go to a subsite and directly change its master page I can browse its library for example:
but when I try check out an item I get a File not found error:
The URL 'parents/_catalogs/masterpage/v4.master' is invalid. It may refer to a nonexistent file or folder, or refer to a valid file or folder that is not in the current Web.
So I assume my attempts to reapply the master page have failed for the subsite.