Please post a public link that we can check out.

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

Type about:preferences<Enter> in the address bar.

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} A small dialog should appear. Click Start In Safe Mode (not Refresh). While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe websites. Are there any problems?

Then restart.

Hi Fred,

Sincere thanks for the reply. I already had done most of what you suggested, but even after taking the additional steps the error continues to occur. I'm afraid none of this makes any difference whatsoever - The error even occurred while running FF in Safe Mode.

Since posting the issue I've also downloaded a fresh copy of FF but continue to have the same issue.

The crazy thing is that it is so erratic... I'm a Microsoft Mac Office MVP dealing primarily with the Microsoft Answers Community. Admittedly, it has its share of problems, but this seems to be isolated to FF in my main User Account. I haven't seen it when using Safari in the same account or in FF when logged in as a different user. In fact, I have a FF window that's been running the circling blue dots for more than 10 minutes. I just copied the URL from that page, pasted it into a Safari address bar & the page loaded without a hitch. Attempting to reload the page in FF responds with the Bad Request message.

After a fresh launch of FF there is no problem. I can switch to any forum & access any thread. Before long, I can simply click the Back button to return to the previous page & the error window appears. Sometimes I can visit a particular thread multiple times but when attempting to it again the error occurs. IOW, it isn't like it's any specific page or circumstance. The only consistent factor is that it will happen & when it does there is no cure but to relaunch FF... but then it will soon start the behavior again.

I'm at a complete loss... Is there a comprehensive list of ancillary & related files that I need to remove in order to wipe out FF altogether? Maybe a completely clean installation of the program will correct it.

FredMcD said

Please post a public link that we can check out.

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Type about:profiles<enter> in the address bar.

Thanks, Fred. I've tried everything you suggested but still have the problem.

Any other thoughts?

As I said before, I'm at a complete loss, but at this rate FF simply is unusable at least for accessing the Microsoft Answers site.

I'm running out of ideas.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
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