Error when importing backup

ok found this code:

    public void loadFileList(XWikiContext context) throws XWikiException
    {
        XWiki xwiki = context.getWiki();
        loadFileList(
            xwiki.getSpacePreferenceAsLong(UPLOAD_MAXSIZE_PARAMETER, UPLOAD_DEFAULT_MAXSIZE, context),
            (int) xwiki.getSpacePreferenceAsLong(UPLOAD_SIZETHRESHOLD_PARAMETER, UPLOAD_DEFAULT_SIZETHRESHOLD, context),
            xwiki.Param("xwiki.upload.tempdir"), context);
    }

So the value of xwiki.upload.tempdir seems to be the value for the repository, and if not writable or cannot create the directory, then it’ll fallback to java.io.tmpdir.

EDIT: Confirmed in the comments of Loading...