Translate Display_Errors from Upload's class

[eluser]Unknown[/eluser]
Hello Phil. Thanks about your answer.

I want to show the upload response to user by AJAX. In the same way, I want to display the message in multilanguage (like Portuguese and Deutsch). The message is default by CodeIgniter and I can't translate it.

So I ask: how can I change the message or translate it?

Thanks in advance.

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@edit

I already know the Internationalization's Library of CI, but its not my case. I need to translate a default CI's message.