Looking at the Error Console was the right idea, thanks. Here's the error that is caught when clicking the "Confirm Security Exception" button:
Exception { name: "NS_ERROR_FAILURE", message: "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIURI.port]", result: 2147500037, filename: "chrome://pippki/content/exceptionDialog.js", lineNumber: 156, columnNumber: 0, data: null, stack: "getURI@chrome://pippki/content/exceptionDialog.js:156:7\naddException@chrome://pippki/content/exceptionDialog.js:386:13\n_fireButtonEvent@chrome://global/content/elements/dialog.js:487:19\n_doButtonCommand@chrome://global/content/elements/dialog.js:466:29\n_handleButtonCommand@chrome://global/content/elements/dialog.js:460:19\nInformUserOfCertError@chrome://messenger/content/mailWindow.js:685:10\nOnStopRunningUrl@chrome://messenger/content/mailWindowOverlay.js:2938:30\n", location: XPCWrappedNative_NoHelper }
The previous
Looking at the Error Console was the right idea, thanks. Here's the error that is caught when clicking the "Confirm Security Exception" button:
Exception { name: "NS_ERROR_FAILURE", message: "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIURI.port]", result: 2147500037, filename: "chrome: //pippki/ content/ exceptionDialog .js", lineNumber: 156, columnNumber: 0, data: null, stack: "getURI@ chrome: //pippki/ content/ exceptionDialog .js:156: 7\naddException @chrome: //pippki/ content/ exceptionDialog .js:386: 13\n_fireButton Event@chrome: //global/ content/ elements/ dialog. js:487: 19\n_doButtonCo mmand@chrome: //global/ content/ elements/ dialog. js:466: 29\n_handleButt onCommand@ chrome: //global/ content/ elements/ dialog. js:460: 19\nInformUserO fCertError@ chrome: //messenger/ content/ mailWindow. js:685: 10\nOnStopRunni ngUrl@chrome: //messenger/ content/ mailWindowOverl ay.js:2938: 30\n", location: XPCWrappedNativ e_NoHelper }
The previous