I have various Firefox installs and do not see any partcular problem with Firefox 36.

However I have been getting quite a few unexplained 503 errors. Often on the support site, and yet the servers seem to be ok from checking with status.mozilla.org. In may case it could be that the problem is unrelated to Firefox, I have not yet been concerned enough to do any serious troubleshooting.

One thing that is change with Firefox 36 and could conceivably be part of the reason you have problems is the ability to use HTTP/2 it is possible to turn that off for test purposes. Toggle the two prefs to false using about:config

1. network.http.spdy.enabled.http2
2. network.http.spdy.enabled.http2draft

• See http://kb.mozillazine.org/About:config

I would advise against downgrading. I am sure whatever the problem there will be a solution or workaround that dos not need downgrading to an unsupported and now unsafe version.

• See (do not) Install an older version of Firefox

This may of course be coincidence and down to some other change. I am not aware of any major faults or problems in Fx 36 having been found or reported.

John99 said

I have various Firefox installs and do not see any partcular problem with Firefox 36. However I have been getting quite a few unexplained 503 errors. Often on the support site, and yet the servers seem to be ok from checking with status.mozilla.org. In may case it could be that the problem is unrelated to Firefox, I have not yet been concerned enough to do any serious troubleshooting. One thing that is change with Firefox 36 and could conceivably be part of the reason you have problems is the ability to use HTTP/2 it is possible to turn that off for test purposes. Toggle the two prefs to false using about:config

1. network.http.spdy.enabled.http2
2. network.http.spdy.enabled.http2draft

• See http://kb.mozillazine.org/About:config

I would advise against downgrading. I am sure whatever the problem there will be a solution or workaround that dos not need downgrading to an unsupported and now unsafe version.

• See (do not) Install an older version of Firefox

This may of course be coincidence and down to some other change. I am not aware of any major faults or problems in Fx 36 having been found or reported.

Well, I tried turning off those 2 items restarted firefox, still same issue. As I stated, the ONLY change on system was update to v36 from v35.0.1. Literally everything else is exactly the same as I had it under 35.0.1. So, I am now looking at lists of changes/updates/fixes and so far not one thing even remotely rings a bell as a possible cause of this issue. And as to the idea of "other changes", there have been NONE. I am, pardon the expression, VERY anal about changes. And, yes I know you do not recommend a downgrade, but if this persists for much longer I may have no other choice. Except maybe giving up on FF and going to another browser. But that would not be made lightly as I really do like FF. A LOT.

I am sure we should be able to make Firefox work for you. It works for me and for the majority of users.

Not an official Mozilla recommendation, but a useful test and workaround: Install the third party Firefox portable ESR (35.3). That will work ,and be a secure Firefox. (If the problem continues you will have proved it is NOT due to Fx36)

• http://portableapps.com/apps/internet/firefox-portable-esr

Install and test that. Confirm it works. Then afterwards we can try and sort out your problems with the Fx36 Release.

You did not say if you had tried this;

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

Under Advanced, Select Network. Look for Configure How Firefox Connects and press the Settings button. Check the settings.

Some problems occurs when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

OK, after much debate, I finally chose a more draconian technique. Since this all started AFTER the update, I backed up all important items and data using the FEBE addon. Then, did a COMPLETE removal of Firefox. A while back I had made the mistake when I had had issues with another update (quite a while back) created a new profile, which still kept all the alterations in about:config. I felt by removing everything completely and restoring to a fresh install everything BUT the configuration data it had to work. AND IT DID. No more problems.

That was very good work. Well Done. Please flag your last post as Solved Problem so other will know.

And you can use Febe to restore your profile. Note: If the problem should return, go back and restore things one by one.

Hi again CyberWolf64. Glad to hear a clean reinstall solved the problem. Thanks for posting back.

Points of information.

1. Removing the program files but not the profiles is what we usually refer to as a clean reinstall. (Removal of the profile is optional, and more extreme; you will lose bookmarks passwords open tabs etc.)
   • See Firefox keeps crashing at startup_try-a-clean-install
2. Using a new profile or using the Reset|Refresh both remove the preferences set by about:config
   • Profile Manager - Create, remove or switch Firefox profiles
   • Refresh Firefox - reset add-ons and settings

• Note sometimes settings may be set by a user.js file. That will override about:config settings. Also there are other methods possible to reset prefs. Reset Firefox preferences to troubleshoot and fix problems

John99 said

Hi again CyberWolf64. Glad to hear a clean reinstall solved the problem. Thanks for posting back.

---

Points of information.

1. Removing the program files but not the profiles is what we usually refer to as a clean reinstall. (Removal of the profile is optional, and more extreme; you will lose bookmarks passwords open tabs etc.)
   • See Firefox keeps crashing at startup_try-a-clean-install
2. Using a new profile or using the Reset|Refresh both remove the preferences set by about:config
   • Profile Manager - Create, remove or switch Firefox profiles
   • Refresh Firefox - reset add-ons and settings

• Note sometimes settings may be set by a user.js file. That will override about:config settings. Also there are other methods possible to reset prefs. Reset Firefox preferences to troubleshoot and fix problems

As to your item #1, as I stated in my last post I backed up all important items using FEBE. It is the ONE addon I NEVER go without when installing FF anytime/anywhere. It has saved my butt more times than I can count.

But, now the BAD news. The speed issue is back BUT not nearly as bad. And I still get the occasional SERVER NOT FOUND error. So it looks like I will have to keep researching this issue some more and see if I can figure out recent addons that may be causative in nature.

And, I will create another thread for ANOTHER glorious issue that was an issue before the complete removal and still shows up. I have read about it on forum BUT NONE of the "fixes" mentioned do anything at all for it. Anyway, that is for another thread.

I note you did open another thread on a new subject:

• When starting Firefox 36 I Sometimes Get a Full Screen Black Screen /questions/1050102

It is probably worth keeping an eye on another thread, and maybe subscribing to it:

• Work around for server not found problems on FF36 /questions/1049998

Speed issues are not easy to troubleshoot, and could be because of connection problems or an overloaded pc for instance. They may also result in connection attempts timing out.

Note Firefox 36.0.1 is out and that includes another fix for a problematic Fx36 change. Does that with either of your problems.

John99 said

Note Firefox 36.0.1 is out and that includes another fix for a problematic Fx36 change. Does that with either of your problems.

OK, I have been updated to FF 36.0.1 for a bit, and SO FAR the Server Not Found has NOT yet happened. Speed is I am beginning to believe maybe leaning towards my service provider, possibly.

Will keep you posted.