CSV uploader throwing errors randomly for identical entries

I’m trying to upload 12000 sku’s (1000 at a time) using the csv uploader.

I’m getting some random errors for identical data.

For example: every cell in the attribute_set_column has a 9, but I get this error

 Invalid value for Attribute Set column (set doesn't exist?) in row(s): 575, 577

Is there any way to fix inconsistencies like this, or at lease get less vague error messages?

Thanks