FF 63 is deployed in our organisation, and we use the autoconfig logic to configure preferences. Since FF 63 autoconfig.js which calls "mozilla.cfg" has stopped processing code following on from the section under the comment "// Disable crash reporter" The segment of code that appears to cause the issue is as follows: "Components.classes["@mozilla.org/toolkit/crash-reporter;1"].getService(Components.interfaces.nsICrashReporter).submitReports = false;" If I comment it out then the code below this is processed successfully. You'll also see in the text of "mozilla.cfg" that I commented out the section altogether and moved it to the section starting... "// ************ Crash reporter code moved as it..." i.e I moved the code to disable Crash Reporter to the end of the file so it executed last. I'm pretty sure the code deosn't execute as it just appears to cause Firefox to 'stall' until it starts. Last bit of evidence, In the Browser Console one of the messages is as follows: "ReferenceError: Components is not defined[Learn More] firefox.cfg:57:1" Any ideas on how to fix this please? our organisation policy is not to submit crash reports to stop data leakage, hence why we want crash reporter disabled. Thanks in advance, Pete The full text of the file "mozill.cfg" is as follows: //************** Service Provider configuration ************** // Disable updater lockPref("app.update.enabled", false); // make absolutely sure it is really off lockPref("app.update.auto", false); lockPref("app.update.mode", 0); lockPref("app.update.service.enabled", false); // Disable Add-ons compatibility checking // Removed but placeholder kept (customer) clearPref("extensions.lastAppVersion"); // Don't show 'know your rights' on first run pref("browser.rights.3.shown", true); // Don't show WhatsNew on first run after every update pref("browser.startup.homepage_override.mstone","ignore"); // Disable the internal PDF viewer // Removed but placeholder kept (customer) pref("pdfjs.disabled", true); // Disable the flash to javascript converter pref("shumway.disabled", true); // Don't ask to install the Flash plugin pref("plugins.notifyMissingFlash", false); //Disable plugin checking lockPref("plugins.hide_infobar_for_outdated_plugin", true); clearPref("plugins.update.url"); // Disable health reporter lockPref("datareporting.healthreport.service.enabled", false); // Disable all data upload (Telemetry and FHR) lockPref("datareporting.policy.dataSubmissionEnabled", false); // Disable crash reporter // lockPref("toolkit.crashreporter.enabled", false); // Components.classes["@mozilla.org/toolkit/crash-reporter;1"].getService(Components.interfaces.nsICrashReporter).submitReports = false; // *************** Service Provider Customisations ****************** // Set default homepage - users can change lockPref("browser.startup.homepage", "about:home|http://internal.urls/"); lockPref("browser.shell.checkDefaultBrowser", false); // Set NTLM Negotiaton Options lockPref("network.negotiate-auth.allow-non-fqdn", true); lockPref("network.negotiate-auth.trusted-uris",".various.urls"); lockPref("network.automatic-ntlm-auth.allow-non-fqdn", true); lockPref("network.automatic-ntlm-auth.trusted-uris", ".various.urls"); // Set use of shared certificate repo lockPref("security.enterprise_roots.enabled", true); // ************ Crash reporter code moved as it appears to be stopping the Service Provider Customisations from running, whic breaks Firefox *************** // Disable crash reporter lockPref("toolkit.crashreporter.enabled", false); Components.classes["@mozilla.org/toolkit/crash-reporter;1"].getService(Components.interfaces.nsICrashReporter).submitReports = false;