I recently upgraded Magento from 1.7 to 1.9. First I upgraded a copy of the live site and all went well.
When I did the same upgrade on the live site I cannot longer create or edit categories. All changes get reverted.
My goal is to change a category's URL Key via
Catalog->Manage Categories->My Category-> URL key
from very-long-category-url-key to short-url-key for example. When I press Save Category it appears to save but the URL key is the same as before I changed it.
I also tried to create a new category and when I press Save Category I get the same Create Category page with blank fields and the category is not created.
Any suggestions on what to look for?