I had another recent challenge with Drupal (again, some other upgrade or change to my web server / database server) where I was no longer able to edit a page after loggging into my Drupal website.
Since I was using PostgreSQL I was able to update a few specific fields in a couple tables when I could no longer update my content on a particular page (node 145). I used pgadmin3 to run this query.
You need to update two different tables to fix the problem with unable to edit a page. Both the node and node_revisions tables need to be updated.
Then run the following code to update the page:
This allowed me to fix it so I could now EDIT the page inside Drupal.
NOTE: This worked for me with Drupal 7. This may not work for you. And any changes you make directly in the database could have other impacts. Validate your data and how Drupal is working (tracing queries, etc) before you directly make changes to your backend database.