Can't Add/ Edit Categories After Upgrading Magento to 1.9.1.0 -

1.9.0.1 to 1.9.1.0 We can not add / edit categories after upgrading Magento. When the catalog / management category is clicked in the admin panel, details of categories are displayed for 1/10 of a second and then disappear. The description of the categories is shown in the front but not in the admin panel. In addition, when you click on a tab (Manage Categories), then "#" is added to the URL. Does anyone know what might be the reason for this problem?

Try adding by adding your php.ini settings:

  phpinfo (); Die; 
 
 
 
 
 
 
 
 
 P> Very few sets, 128 MB are likely to be. 
 
 Extend it till 256/512/1024/2048 until it is satisfied.