I got this error when I did Catalog > Manage Categories
And this error when I did Catalog > Manage Products > Add Products > Continue
I already contacted my hosting, and they said that my problems are not connected directly to their services, server software and/or modules installed on the server..
They gave me these recommended links to me, but I don't understand any of them,
https://magento.stackexchange.com/questions/44733/source-model-not-found-for-attribute
https://magento.stackexchange.com/questions/28905/source-model-not-found-for-attribute-industry
https://magento.stackexchange.com/questions/57975/source-model-not-found-for-attribute-catcustomergr...
I really hope that someone in Magento Forums could help me, because I cannot add any products into my website.
Thanks in advanced.