When I am trying to access
Catalog > Manage categories, I am having the below error:
Source model "defaultcatview/category_attribute_source_view" not found for attribute "default_cat_list_view"
It looks like you have installed a third pary module, and you don't uninstalled this in the right form.
I think that an attribute in database table
eav_attribute are making the conflict.
Execute this SQL code in your database:
DELETE FROM eav_attribute WHERE attribute_code = 'default_cat_list_view';