Author Topic: Avast restarts Firefox?  (Read 1034 times)

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Offline cloudSVR

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Avast restarts Firefox?
« on: March 05, 2019, 07:37:41 AM »
Windows 7 Ultimate SP1 64-bit
Program version: 19.2.2364 with latest definitions.

At random times I get this message and when I click OK Firefox restarts itself. I actually reinstalled Avast making the message gone but the random restarts still happen just without the prompt. What can be done to fix this?

Offline bob3160

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Re: Avast restarts Firefox?
« Reply #1 on: March 05, 2019, 02:23:46 PM »

Repair Avast:
Control Panel> Program and Features (Add/remove program)>Select Avast> Select Repair. Reboot when completed
If Repair doesn't fix the problem, try the following:
Clean Install of Avast:
Free avast! Security Seminar:  -  Important: -- My Web Site: - Win 11 Pro v21H2 64bit, 16 Gig Ram, 1TB SSD, AvastOmni 21.6, How to Successfully Install Avast & Clean Install

Offline cloudSVR

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Re: Avast restarts Firefox?
« Reply #2 on: March 13, 2019, 12:02:10 PM »
Sorry for the delayed reply but I tried both steps and I still get the same problem, I guess it's Firefox causing it I'll try re-installing thanks.

Offline kwiq

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Re: Avast restarts Firefox?
« Reply #3 on: March 13, 2019, 12:46:37 PM »
Hi cloudSVR
Try to update to new vps version and restart Firefox.
CloseBrowser is one of exported functions from bcuengin.dll.

If the issue will happen again please zip bcuengin.dll as and upload to

Which version of firefox you have and is it x86 of x64?
Thank you for report !

Offline just52

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Re: Avast restarts Firefox?
« Reply #4 on: April 23, 2019, 02:25:08 PM »
I have the same problem since start of March 2019 (approximately)
I have had the message shown by cloudSVR but now with the last versions of avast and firefox, i haven't the message anymore
When i had the message i could see that bcuengine.dll was launched by avastsvc through rundll32.
As soon as i clicked on the ok button, firefox was closed.

Twice a day, every 12 hours approximately, firefox closes and restarts (sometimes it doesn't restart)
I uninstalled avast (using avast uninstall tool) and reinstalled it but the problem is still here.
I tried deactivating all firefox extensions, i also tried to deactivate all avast agents but the problem was still here.
If i use google chrome and define it as default browser instead of firefox, there is no such behaviour.

My current versions :
Windows 7 professionnal 64 bits (up to date)
avast 19.4.2374 (version 19.4.4318.455)
vps 190423-0
firefox 66.0.3 (64 bits)