+++ This bug was initially created as a clone of Bug #827134 +++ This bug for resloving QI error of nsLoginManager. [Environment] * http://hg.mozilla.org/mozilla-central/rev/20d1a5916ef6 [STR] 1. Start "Browser Debugger" & set "Pause on exceptions" 2. Open passward manager, OR execute following code: (function(){ let origin = Service.io.newURI(document.documentURI, null, null).prePath; let matchData = Cc["@mozilla.org/hash-property-bag;1"] .createInstance(Ci.nsIWritablePropertyBag); matchData.setProperty("hostname", origin); let savedLogins = Services.logins.searchLogins({}, matchData); ])(); [Result] Browser Debugger pauses Firefox many times with the error "2147500034". Their stack trace will show http://hg.mozilla.org/mozilla-central/file/c4abfca219e5/js/xpconnect/loader/XPCOMUtils.jsm#l332. [Stack trace] This trace is when opening password manager: XPCOMUtils_QueryInterface: XPCOMUtils.jsm:332 Startup:passwordManagerCommon.js:30 onload: passwordManager.xul:1