'Sorry, but the data is invalid or the file is not uploaded.'

[pefferen]

We encountered some problems while importing via the importexportfree module, both error cases resulted in an undescriptive error message, which makes an analysis of the import file difficult, can the error message be more explicit? the problem we encountered in the import files:

• A product with a different SKU with the same url_key already exists.
• Quotes in the column additional_attributes

Both cases result in the error message 'Sorry, but the data is invalid or the file is not uploaded.' which is not very helpful for the user.

this issue duplicates or possible replace #32

[Hembi]

Please add a more explicit error message.