SharePoint Designer 2010: This page cannot be edited in SharePoint Designer

Problem

You connect to a SharePoint 2010 farm site through SharePoint Designer 2010 in order to edit a page at the site.  After successfully connecting to the site and checking out the page, when you then click the Edit link, you experience this prompt:

Solution

1. On seeing this prompt, click Cancel.
2. Undo the checkout.
3. Go to a list view of the pages
4. Select the page.
5. On the All Files ribbon, click the Detach from page Layout button.
6. Proceed to edit as normal.

References

• Managing SharePoint Designer 2010
• Publishing features overview (SharePoint Server 2010)
• Create and manage publishing pages