You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in simplesamlphp 's PO files:

gettext: locales/st/LC_MESSAGES/attributes.po:8: end-of-line within string
locales/st/LC_MESSAGES/attributes.po:435: keyword "Lebitso" unknown
locales/st/LC_MESSAGES/attributes.po:435:17: syntax error
locales/st/LC_MESSAGES/attributes.po:436: end-of-line within string
locales/st/LC_MESSAGES/attributes.po:438: keyword "Lebitso" unknown
locales/st/LC_MESSAGES/attributes.po:438:17: syntax error
locales/st/LC_MESSAGES/attributes.po:439: end-of-line within string
locales/st/LC_MESSAGES/attributes.po:441: keyword "Lebitso" unknown
locales/st/LC_MESSAGES/attributes.po:441:17: syntax error
locales/st/LC_MESSAGES/attributes.po:442: end-of-line within string
msgfmt: found 10 fatal errors
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.