A few weeks ago, Avast! stopped being able to update, “Downloading files: servers.def.vpx” “Unknown Error”.
I then installed Avast! on another PC, but I had to use the offline installer, the web install wouldn’t proceed. After this was installed, it wouldn’t update, either.
I WiFi connected to another Internet Service Provider, then was able to update on the original PC.
Connected WiFi back to original ISP, again won’t connect to update servers.
Investigating further…
Providing more information, but no progress (sorry)…
I am in Australia. I can get Internet over the NBN (National Broadband Network, (mostly) fibre infrastructure). Also over MWB (Mobile Wireless Broadband, mobile phone infrastructure).
My Dodo NBN, about 4 weeks ago, Avast! stopped being able to update. Also could not use the web installer.
2 weeks ago, I moved house (by about 5 kilometres), now have Belong Broadband NBN. Avast! still won’t update, cannot use the web installer.
But then connected to Internet using Telstra MWB, and Avast! updates. I can switch back and forth from Telstra MWB to Belong NBN, repeating the update failure with Belong NBN, and update success with Telstra MWB.
Am experimenting further, hoping to find a >ping or >traceroute that fails for one and succeeds with the other.
Perform a clean installation of the latest avast version with the off-line installer and check if the problem is solved.
If not, provide more information
What OS/SP ?
What exact version of avast (version + build) ?
Any other security software installed ? (or was there)
Any other problems with the system ?
Are you connection true a wire or WiFi ?
Thanks for reply, Eddy.
It may be 5 or 6 hours before I get back to you, as I have to go and do a job.
I have many OSs on various PCs, I will choose a fresh one and try what you say, and report back.
I suspect the problem is not with Avast!.
Take your time.
It is 00:40h at my place.
Gonna sleep soon.
Give the clean installation (use avastclear also) a go.
Let’s see if it changes things or not.
PC: Win10x64 Home Th3 1607 AA en-US:
Had not been started for some months, already had Avast! on it.
Avast! 12.3.2280 (build 12.3.3154.23)
Virus Defs 170127-3
Connected to Belong NBN Internet.
Auto-updated definitions by itself, to 170512-8, also no errors when update initiated manually.
Tried to web-install Avast!, got
There was an error while completing the setup process
Copied error log into attached text file.
Experiments continue…
I did suggest to perform a clean installation with the off-line installer.
PC: Win7x86 HomePrem SP1 en-US:
No antivirus has ever been installed on this PC.
Connected Internet Belong NBN.
Used Avast! offline installer 17.4.3482.0
Custom Protection, File Shield only
Installation completed,
Prog vers: 17.4.2294 (build 17.4.3482.0)
defs: 170502-2
Manually starting def update…
Step 1/2
Initializing, please wait…
about 5 mins…
Downloading file: servers.def.vpx
Unknown error
Downloading file: prod-pgm.vpx
Unknown error
Nothing downloaded
Server: Download r5525652 AVAST9 Server
http://r5525652.vpsnitro.u.avast.com/vpsnitro
Did you use avastclear ?
Where did you get the off-line installer from ?
Did not use avastclear.
Got installer from http://files.avast.com/iavs9x/avast_free_antivirus_setup_offline.exe
See reply #6
I had a similar issue with Avast Premier.
I also did a remove , clean and reinstall to no avail
However, in my Avast Settings, I set Proxy to “Direct connection” voila… update success 
NGA
Thanks for taking the time to report your resolution, it could well help others.
Though I thought Direct connection was the default option. I think it would only be off if you specified a proxy server.
+1
What I’ve got: (and no connection issues either)
I’ve never touched this setting or changed it to proxy as I would have to specify what proxy I want to use.
As far as I know, it is the default setting.
I have found a workaround.
After noting that
nslookup w6607332.vpsnitro.u.avast.com
produces
Server: belong.gateway
Address: 10.0.0.138
DNS request timed out.
timeout was 2 seconds.
Non-authoritative answer:
DNS request timed out.
timeout was 2 seconds.
Name: a1639.g1.akamai.net
Addresses: 72.247.223.43
72.247.223.26
Aliases: w6607332.vpsnitro.u.avast.com
avast.com.edgesuite.net
and has the same timeouts with other addresses like www.microsoft.com and www.avast.com,
when connected to the Internet through Belong NBN,
and these timeouts do not occur when connected through Telstra MWB,
I suspected a DNS issue.
The workaround:
Manually set the Connection’s DNS to
8.8.8.8 and
8.8.4.4
(Google Public DNS).
Avast! updates fine after applying this.
But I should not be using this workaround permanently.
I will be speaking to my ISP (Belong) about this.
Retested using the Dodo NBN Internet connection, without the workaround.
No timeouts when using >nslookup.
Avast! online installer went to completion with no problems.
Can update definitions with no problems.
This is not how it was 3 to 4 weeks ago (which is good).
A more refined workaround:
My modem/router at 10.0.0.138 is normally my Connection’s IPv4 DNS.
Manually set the DNS to
10.0.0.138 and
8.8.8.8
8.8.8.8 will only be used when 10.0.0.138 fails.
Now using this workaround:
In my connection’s TCP/IPv4 DNS settings:
155.143.128.19
155.143.254.19
I plucked these addresses from the Belong NBN modem, after having recurring trouble, when using the previous workaround(s), of the internet access stopping after {[a few hours] and/or [rebooting one of the computers] and/or [something else?]}, and having to {[reboot] and/or [restore to factory settings]} the modem (did not actually try the modem reboot option alone), to restore internet access.
Update:
Workaround not required on a WinXPx86 PC.
Sorry for Necro :-
Had exact same problem, avast stopped updating with unknown error, won’t web-install, only offline-install with no updates either. Different PCs, same ISP.
Switching to google public DNS did help. Like a charm i might add.
It’s rather weird to use DNS to update a program imo… can’t they tell what their own server’s IPs are?