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Firefox seems intermittently to lose track of Proxy settings, just reloading the PAC file in the Proxy Settings dialog resolves it temporarily.

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  • 2 have this problem
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  • Last reply by Sinbad2000

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So every now and then, FF Quantum 58.0b12 (64-bit), Windows 7 Enterprise tells me I'm not connected to the internet. My company requires a proxy, and has a PAC file set up, which is configured in FF.

When the error page pops up, I open Options / Proxy settings and hit "Reload" on the pac file field, and then I can refresh the page that was not working. This will work for an indeterminate period, and then suddenly all my tabs will show "not connected" again.

I do not experience this issue with Chrome or Edge.

So every now and then, FF Quantum 58.0b12 (64-bit), Windows 7 Enterprise tells me I'm not connected to the internet. My company requires a proxy, and has a PAC file set up, which is configured in FF. When the error page pops up, I open Options / Proxy settings and hit "Reload" on the pac file field, and then I can refresh the page that was not working. This will work for an indeterminate period, and then suddenly all my tabs will show "not connected" again. I do not experience this issue with Chrome or Edge.

All Replies (5)

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Try not running a Beta Release : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer

Please let us know if this solved your issue or if need further assistance.

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Pkshadow said

Try not running a Beta Release : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer Please let us know if this solved your issue or if need further assistance.

Hi there Rolling back to 57 did indeed resolve the issue for me.

However, an automatic update to 58 caused it to come back.


Just updated to 58.0.1 and monitoring...

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Confirmed, still occurring with 58.0.1

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Sinbad2000 said

Pkshadow said
Try not running a Beta Release : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer Please let us know if this solved your issue or if need further assistance.

Hi there Rolling back to 57 did indeed resolve the issue for me.

However, an automatic update to 58 caused it to come back.


Just updated to 58.0.1 and monitoring...

What was said was to remove FF not do a roll back update. If you did this then the problem most likely was still there and remains there. To verify there is no problem a removal of FF and any Mozilla folders is what is advised to clear up any problems before installing FF58.0.1 to see if the problem was resolved. Also make sure the FF bit version matches the O/S version so don't install FFx86 on a x64 O/S but to install FFx64 on x64 O/S.

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Hi To clarify, I meant rollback in the logical sense. I did a complete uninstall and reinstall of 57.0 and had no problems. Yesterday there was an automatic update to 58.0 and then 58.0.1 in which the problem manifests.

Thanks