User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0 Build ID: 20140716183446 Steps to reproduce: Attempt to install Bulgarian localization xpi for Firefox 31.0 from: http://download-origin.cdn.mozilla.net/pub/mozilla.org/firefox/releases/31.0/win32/xpi/bg.xpi Actual results: The xpi is not installed. Error message: The add-on downloaded from ... could not be installed because it appears to be corrupt. Expected results: The xpi should be installed. The workaround is to unpack the xpi, remove two empty lines from the beginning of install.rdf, repack and retry.
Confirmed with fx34
Oh my, I reported this issue back in 2014-06-13 https://bugzilla.mozilla.org/show_bug.cgi?id=1025437 I thought it was long lost as it never got replied to until recently. This bug has been present for a long time.