Rozwiązanie z bloga http://www.oracleebstech.com/2011/10/xliff-translation-upload-error/
Problem: When uploading a XLIFF translation file for a BI Publisher template, you get the following error:
“The uploaded translation file is invalid. It should specify a valid target language and territory. Please verify that the file is in the correct format.”
A possible cause for this error is the encoding defined in the xml file. Probably it is defined as ‘UTF-8’. Change it to something else, like ‘WINDOWS-1252’ Dla polskich znaków WINDOWS-1250
Another possibility is for the XLIFF to be in an incorrect XML format. I suggest running it through a XML validator, like http://www.xmlvalidation.com.