Firefox error message: A required privilege is not held by the client.

Web search; https://www.bing.com/search?q=required+privilege+is+not+held+by+the+client

Did you use the normal install or make changes?

Thank you for that search/links. I have tried a normal install and with administrator privileges, and with the anti-virus deactivated.

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

In safe mode with network support the installation progress bar reached about 90% then stopped with the following error message:

Firefox Installer. Hmm. For some reason we could not install Firefox. Choose OK to start again.

I called for more help.

OK, I appreciate that.

Eddie said

I tried to open Firefox yesterday and got the following error message: Mozilla-Firefox 64bit. A required privilege is not held by the client. I uninstalled Firefox thinking that reinstalling would fix the problem but when I attempted to reinstall Firefox I got the same error message. This is on a Windows 10 64bit machine.

Had the same problem; started in safe mode and it was gone. And I also reinstalled Firefox before.

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems.

Solved problem.