If you take a look at these lines then yo notice wrong quotation marks. Only the first is a ", the others are Unicode quotes (“ and ”) and this throws an exception.

• pref("browser.startup.homepage","http://www.google.co.uk/”);
• pref("browser.startup.homepage_override.mstone”, “ignore”);

Some lines lack a trailing ';'.

Note that app.update.enabled is no longer supported in Firefox 63+, there is only app.update.auto left (bug 1420514).

//Firefox Default Settings

// set Firefox Default homepage
pref("browser.startup.homepage","http://www.google.co.uk/");

// disable default browser check
pref("browser.shell.checkDefaultBrowser", false);
pref("browser.startup.homepage_override.mstone", "ignore");

// disable application updates
pref("app.update.auto", false);
pref("app.update.enabled", false);

// disables the ‘know your rights’ button from displaying on first run
pref("browser.rights.3.shown", true);

// disables the request to send performance data from displaying
pref("toolkit.telemetry.prompted", 2);
pref("toolkit.telemetry.rejected", true);

// disable history, download, cache, password and settings
pref("browser.privatebrowsing.autostart", true);

// clear cookies
pref("privacy.clearOnShutdown.cookies", true);

cor-el said

If you take a look at these lines then yo notice wrong quotation marks. Only the first is a ", the others are Unicode quotes (“ and ”) and this throws an exception.

• pref("browser.startup.homepage","http://www.google.co.uk/”);
• pref("browser.startup.homepage_override.mstone”, “ignore”);

Some lines lack a trailing ';'. Note that app.update.enabled is no longer supported in Firefox 63+, there is only app.update.auto left (bug 1420514).

//Firefox Default Settings

// set Firefox Default homepage
pref("browser.startup.homepage","http://www.google.co.uk/");

// disable default browser check
pref("browser.shell.checkDefaultBrowser", false);
pref("browser.startup.homepage_override.mstone", "ignore");

// disable application updates
pref("app.update.auto", false);
pref("app.update.enabled", false);

// disables the ‘know your rights’ button from displaying on first run
pref("browser.rights.3.shown", true);

// disables the request to send performance data from displaying
pref("toolkit.telemetry.prompted", 2);
pref("toolkit.telemetry.rejected", true);

// disable history, download, cache, password and settings
pref("browser.privatebrowsing.autostart", true);

// clear cookies
pref("privacy.clearOnShutdown.cookies", true);

Thanks for your responce, I tried the config you posted and this also didn't work, and I had the same error message. If I delete my xxx file then I still get the error, only deleting the local-settings file does the problem go away.

My local-settings js file is:

pref("general.config.obscure_value", 0); pref("general.config.filename", "mozilla.cfg");

If i delete this file then it works ok, but we would like to do the customization's. I checked the file permissions and they were ok. I am pretty stomped!

Thanks for your help, Merry Christmas!

Where is the mozilla.cfg file located?

The mozilla.cfg file should be in the main Firefox program folder and not in the same folder as local-settings.js

Also make sure mozilla.cfg is a plain text file and doesn't have a hidden .txt file extension.

cor-el said

The mozilla.cfg file should be in the main Firefox program folder and not in the same folder as local-settings.js

This was the issue! Thank you very much for your help, I greatly appreciate it. Thanks again,

Alexander

When I started Firefox, the "failed to read the configuration file" msg popped up, I clicked OK, then Firefox loaded ok. I searched for non-standard .js files in the mozilla firefox subdirectory and found antibeacon.js in addition to the channel-prefs.js that's supposed to be there. That file is part of spybot antibeacon that's supposed to block primarily microsoft spying. Anyway, I moved that antibeacon.js file and when I next started firefox, no error msg appeared. Unfortunately when when I applied antibeacon protections, the file reappeared, Since antibeacon reapplies at startup this may be an ongoing annoyance.

If your problem is caused by Spybot then you need to contact them for support. It is likely that this file is no longer compatible with Firefox.

You can check the Browser Console for more detail about what is wrong.

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

Per your suggestion, I reported the problem to spybot. Here's a link to that thread in case others want to pursue it. * https://support.mozilla.org/en-US/questions/1244793#answer-1184625

The issue appears to affect the 64bit version of firefox, but a brief experiment with an n=3 shows that 32-bit firefox opens without the "failed to read the configuration file" msg and there was no antibeacon.js file in the Mozilla Firefox x86 directory which is used by 32bit firefox.