It looks like the file is XLIFF 2.0 and the error is one that would occur in 1.4. I’m guessing you are trying to process a 2.0 XLIFF with a 1.4 filter. Could you give more info on what tool generates the error?
There is an XLIFF2 filter available. For example with Tikal try:
tikal.bat -x sample.xliff -fc okf_xliff2
Your file will be processed (extracted to an XLIFF 1.4 file) without error.