"PR_END_OF_FILE_ERROR" using Firefox

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Patate

New Member
Hi!

I have installed AdGuard 7.6.1 on my partner's computer, with a standard lifetime license. They use Firefox and have been having trouble accessing some websites while it is on, with the same error message : PR_END_OF_FILE_ERROR
The first time they saw it was when trying to log in their youtube account -and then twitter as well.

I did some investigating and also got it when trying to access support.mozilla.org but was able to log into twitter.
Disabling AdGuard makes the error message disappear.
Disabling DNS protection only works in the first few seconds / minutes, the error message is back not long after.
Disabling stealth mode doesn't change anything, the error message is still here.

Thank you for your time :)
 
Boo Berry

Boo Berry

Moderator + Beta Tester
Moderator
Can you confirm that AdGuard for Windows' certificate is installed in Firefox? If not, that's probably why.
 
H

Hyperspace

New Member
I discovered what the problem is. It's the WFP network driver on Adgaurd that was causing the problem. Turn it off and Firefox works perfectly. I discovered it by accident because for the past 2 weeks something was causing my router to crash multiple times a day. I needlessly replaced my router and that didn't solve the problem. Replaced my coax and fittings and that didn't solve the problem. Reinstalled Windows and that didn't solve the problem. Updated all my network drivers and that didn't solve the problem. Then I started looking at Adgaurd and turning settings off and back on and discovered it was the WFP network driver that was causing all the problem. Turned it off and no more router crashes. Then I discovered Firefox now works like it should.

I needlessly went through 2 weeks of hell troubleshooting everything only to find out it was Adguard. I wish I would have started with that then it would have saved me time, money, and headaches.
 
J

jsgjunk

New Member
Hyperspace said:
...WFP network driver that was causing all the problem. Turned it off and no more router crashes. Then I discovered Firefox now works like it should.

I needlessly went through 2 weeks of hell troubleshooting everything only to find out it was Adguard. I wish I would have started with that then it would have saved me time, money, and headaches.
Click to expand...
I've been struggling with this for a while. I followed your suggestion here and it seems to have fixed it! I have been having router issues as well and I had no clue AdGuard could have been the culprit. Hopefully the router issues stop as well. Thank you!
 
Boo Berry

Boo Berry

Moderator + Beta Tester
Moderator
If disabling the WFP driver fixes it, there has to be some other software (e.g. antivirus) running on your PC causing an incompatibility with the WFP driver.
 
J

jsgjunk

New Member
Boo Berry said:
If disabling the WFP driver fixes it, there has to be some other software (e.g. antivirus) running on your PC causing an incompatibility with the WFP driver.
Click to expand...
Thanks for your reply. It seems to be specific to Firefox. I tried with Edge and Chrome and they both work fine. I've messed around with the settings in Firefox and I can't seem to figure out which setting conflicts. Any ideas?
 
R

ralfy

New Member
I'm experiencing the problem now, but only for Firefox and Adguard for Windows: I'm able to visit a site, but after a few minutes the error occurs. There's no problem when I load the same site in Edge.

The problem comes and goes. When I load a page, the problem shows up. When I reload repeatedly, the page eventually shows up at the third try or so.
 
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R

ralfy

New Member
The problem does disappear when I disable the WFP driver. I tried disabling the Avast free web shield but it persisted. The same happened when I disabled the Adguard browser security.
 
A

AYHJA

New Member
I also use Avast. I did a fresh install of AdGuard with Windows Defender as the default, before I installed Avast, and still encountered the error with the WFP driver. If there is a potential conflict with my AV (necessary) and Adblock (also necessary) it's a priority for me to figure out what that incompatibility is and address it if at all possible.

I'll do some research on my own to figure out exactly what the WFP driver is and what parts of an AV may prevent it from working. But in the meantime, can someone share some insight as to why it seems to affect one browser more so than the other.? Edge works a little better than Firefox with the WFP driver active, but both of them perform as expected with it disabled.
 
H

H3lper

Support
Staff member
Administrator
Moderator
AYHJA said:
I also use Avast. I did a fresh install of AdGuard with Windows Defender as the default, before I installed Avast, and still encountered the error with the WFP driver. If there is a potential conflict with my AV (necessary) and Adblock (also necessary) it's a priority for me to figure out what that incompatibility is and address it if at all possible.

I'll do some research on my own to figure out exactly what the WFP driver is and what parts of an AV may prevent it from working. But in the meantime, can someone share some insight as to why it seems to affect one browser more so than the other.? Edge works a little better than Firefox with the WFP driver active, but both of them perform as expected with it disabled.
Click to expand...
We usually advise excluding AdGuard and AV from filtering mutually as they interfere with each other. So, to do so, head to AdGuard>Settings>General>Advanced>Exclude app from filtering by entering the full path> enter the full path to .exe. file of your AV

Let me know how it works
 
S

shajeeafzal

New Member
I am having the same issue. I have Avast + AdGuard.

I have installed the certificate in windows as well as firefox. I am still unable to view the websites due to the same "PR_END_OF_FILE_ERROR" error.

Can someone provide a valid solution apart from unchecking the "WFP" drivers option?

@H3lper, you said to exclude AV in the AdGuard app. However, Avast has multiple .exe files (around 6, 7). Which one should I exclude?

@AYHJA were you able to figure it out? @ralfy you too?
 
H

H3lper

Support
Staff member
Administrator
Moderator
shajeeafzal said:
I am having the same issue. I have Avast + AdGuard.

I have installed the certificate in windows as well as firefox. I am still unable to view the websites due to the same "PR_END_OF_FILE_ERROR" error.

Can someone provide a valid solution apart from unchecking the "WFP" drivers option?

@H3lper, you said to exclude AV in the AdGuard app. However, Avast has multiple .exe files (around 6, 7). Which one should I exclude?

@AYHJA were you able to figure it out? @ralfy you too?
Click to expand...
AdGuard must be excluded from Avast in the first place, as it interferes with AdGuard mostly, yet you can add them all. Plus, if there's any Real-time web protection or so – disable it as well.
That should actually fix it. However, there's nothing bad if you disable WFP driver.
 
J

Jason120831

New Member
shajeeafzal said:
I am having the same issue. I have Avast + AdGuard.

I have installed the certificate in windows as well as firefox. I am still unable to view the websites due to the same "PR_END_OF_FILE_ERROR" error.

Can someone provide a valid solution apart from unchecking the "WFP" drivers option?

@H3lper, you said to exclude AV in the AdGuard app. However, Avast has multiple .exe files (around 6, 7). Which one should I exclude?

@AYHJA were you able to figure it out? @ralfy you too?
Click to expand...
I found the issue where Adguard is interfering with Avast Antivirus or rather the other way around, it seems to be specifically from the Avast Web Shield. You have to disable the "Enable HTTPS scanning" from the Avast Web Shield settings. The error will disappear not that long. You can leave the "enable QUIC/HTTP3 scanning" enabled.
 
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