You can create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

I've tried with a new profile. No joy. Even the developer console won't open. Security software wouldn't block that or the Options page, would it?

What changed between 57 and 58 that would cause this problem? I would have expected 57 to be broken because of Quantum, but why does 57 work but not 58?

Do you see any error messages in the Browser Console?

• https://developer.mozilla.org/en-US/Tools/Browser_Console

Clicking Web Console does nothing, but launching with -jsconsole show errors:

NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1038
    construct chrome://global/content/elements/browser-custom-element.js:1038
    connectedCallback chrome://global/content/elements/browser-custom-element.js:311
    _setupInitialBrowserAndTab chrome://browser/content/tabbrowser.js:343
    init chrome://browser/content/tabbrowser.js:35
    onDOMContentLoaded chrome://browser/content/browser.js:1283
    onDOMContentLoaded self-hosted:974
TypeError: browser.webProgress is null[Learn More] tabbrowser.js:384:5
    _setupInitialBrowserAndTab chrome://browser/content/tabbrowser.js:384
    init chrome://browser/content/tabbrowser.js:35
    onDOMContentLoaded chrome://browser/content/browser.js:1283
    onDOMContentLoaded self-hosted:974
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152"  data: no]
    _sendMessage jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:152
    loadURI jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:94
    _loadURI chrome://browser/content/browser.js:1077
    _loadURI self-hosted:1020
    loadTabs chrome://browser/content/tabbrowser.js:1539
    loadOneOrMoreURIs chrome://browser/content/browser.js:2213
    _handleURIToLoad chrome://browser/content/browser.js:1697
    _callWithURIToLoad chrome://browser/content/browser.js:1850
    _handleURIToLoad chrome://browser/content/browser.js:1641
    _delayedStartup chrome://browser/content/browser.js:1439
    _delayedStartup self-hosted:974
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal]
browser-custom-element.js:1038
    construct chrome://global/content/elements/browser-custom-element.js:1038
    connectedCallback chrome://global/content/elements/browser-custom-element.js:311
    createBrowserElement resource://gre/modules/ExtensionParent.jsm:1166
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559"  data: no]
    _onExtensionBrowser resource://gre/modules/ExtensionParent.jsm:559
    emit resource://gre/modules/ExtensionCommon.jsm:310
    build chrome://extensions/content/parent/ext-backgroundPage.js:39
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152"  data: no]
    _sendMessage jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:152
    loadURI jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:94
    loadURI chrome://global/content/elements/browser-custom-element.js:815
    _wrapURIChangeCall chrome://global/content/elements/browser-custom-element.js:758
    loadURI chrome://global/content/elements/browser-custom-element.js:814
    build chrome://extensions/content/parent/ext-backgroundPage.js:41
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559"  data: no]
    _onExtensionBrowser resource://gre/modules/ExtensionParent.jsm:559
    emit resource://gre/modules/ExtensionCommon.jsm:310
    build chrome://extensions/content/parent/ext-backgroundPage.js:39
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152"  data: no]
    _sendMessage jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:152
    loadURI jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:94
    loadURI chrome://global/content/elements/browser-custom-element.js:815
    _wrapURIChangeCall chrome://global/content/elements/browser-custom-element.js:758
    loadURI chrome://global/content/elements/browser-custom-element.js:814
    build chrome://extensions/content/parent/ext-backgroundPage.js:41
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559"  data: no]
    _onExtensionBrowser resource://gre/modules/ExtensionParent.jsm:559
    emit resource://gre/modules/ExtensionCommon.jsm:310
    build chrome://extensions/content/parent/ext-backgroundPage.js:39
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210
[Exception... "Component not initialized"  nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"  location: "JS frame :: jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152"  data: no]
    _sendMessage jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:152
    loadURI jar:file:///C:/PortableApps/FirefoxPortable/App/Firefox/omni.ja!/components/RemoteWebNavigation.js:94
    loadURI chrome://global/content/elements/browser-custom-element.js:815
    _wrapURIChangeCall chrome://global/content/elements/browser-custom-element.js:758
    loadURI chrome://global/content/elements/browser-custom-element.js:814
    build chrome://extensions/content/parent/ext-backgroundPage.js:41
    InterpretGeneratorResume self-hosted:1255
    next self-hosted:1210

Does anything in the console indicate what the problem might be?

There are a bunch of references to a PortableApps folder, which is not normal for a standard Firefox installation. Did you migrate a profile from a PortableApps folder to a normal Firefox folder?

If this is a PortableApps installation, maybe try to reinstall it or check permissions/privileges. They also offer support.

If this is supposed to be a Firefox installation, and it's not a migrated profile, then:

Clean Reinstall

This takes about 5 minutes. It's not about your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. It's not essential to uninstall Firefox, but you can if you like, saying No to any request about removing personal data.

(A) Download a fresh installer for Firefox to a convenient location, either:

• Standard Release (Firefox 66): https://www.mozilla.org/firefox/all/
• Extended Support Release of Firefox 60: https://www.mozilla.org/firefox/organizations/all/

(B) Exit out of Firefox (if applicable).

If you use Microsoft Office, please change your default browser to Internet Explorer temporarily before the next step.

(C) Using Windows Explorer/My Computer (hold down the Windows key and press E to launch it), right-click > rename the program folder as follows (you might have one or both):

C:\Program Files (x86)\Mozilla Firefox =to=> C:\Program Files (x86)\OldFirefox

C:\Program Files\Mozilla Firefox =to=> C:\Program Files\OldFirefox

(D) Run the installer you downloaded in step (A). It should automatically connect to your existing settings.

Any improvement at your next startup?

I tried installing a fresh copy of Firefox 66, starting in Safe Mode, clicking Refresh Firefox, and deleting the old profile, but Firefox still won't open Add-Ons , Options, about:config or other web pages. Also if I select Customize Firefox nothing happens when I click Done.

NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1038 [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559" data: no] [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: jar:file:///C:/Program%20Files/Mozilla%20Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152" data: no] [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559" data: no] [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: jar:file:///C:/Program%20Files/Mozilla%20Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152" data: no] [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: resource://gre/modules/ExtensionParent.jsm :: _onExtensionBrowser :: line 559" data: no] [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: jar:file:///C:/Program%20Files/Mozilla%20Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152" data: no] NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1038 TypeError: browser.webProgress is null[Learn More] tabbrowser.js:384:5 [Exception... "Component not initialized" nsresult: "0xc1f30001 (NS_ERROR_NOT_INITIALIZED)" location: "JS frame :: jar:file:///C:/Program%20Files/Mozilla%20Firefox/omni.ja!/components/RemoteWebNavigation.js :: _sendMessage :: line 152" data: no] NS_ERROR_XPC_GS_RETURNED_FAILURE: ServiceManager::GetService returned failure code: nsUrlClassifierListManager.js:65 NS_ERROR_XPC_GS_RETURNED_FAILURE: ServiceManager::GetService returned failure code: SafeBrowsing.jsm:135 TypeError: this.frameLoader.tabParent is null[Learn More] browser-custom-element.js:679:7

   get hasContentOpener chrome://global/content/elements/browser-custom-element.js:679
   checkEmptyPageOrigin chrome://browser/content/browser.js:7305
   get_isEmpty chrome://browser/content/tabbrowser.xml:2084
   switchToTabHavingURI chrome://browser/content/browser.js:7654
   openPreferences chrome://browser/content/utilityOverlay.js:854
   oncommand chrome://browser/content/browser.xul:1