Google 404 in Internet explorer when using Zscaler App

(Tony Odonnell) #1

When entering an address into the IE address bar a Google 404 page is returned.
This happens for valid addresses such as: or
This is an intermittent problem and if searching Google for the same sites and clicking on the same URLs the loads.

we are using the Zscaler app with tunnel mode and packet based tunnel driver type.

has anyone else had this issue?

(Scott Bullock) #2

Hi Tony, I’m using Zscaler App for ZIA and ZPA all day every day, on multiple systems, and have never seen this. Do you have a support ticket open? It sounds like some advanced analysis and diagnostics will need to be taken.

(Tony Odonnell) #3

Yes, I do have a ticket open.
I was testing yesterday and found that when browsing to HTTP://MSN.CO.UK which should redirect to HTTPS://WWW.MSN.COM/EN-GB there is often a problem. It’s not always the Google 404 sometimes the page doesn’t load or sometimes it produces an error on the website.
This doesn’t happen with Google Chrome at all.
I realise that this suggests the problem lies with IE but this is what our company & many others use by default. I have also tested on my home PC and got similar issues (not Google 404 but pages not loading).

I like the fact that the ZIA with tunnel mode enable captures traffic from applications that aren’t proxy aware and makes them work but at the moment it looks like we are going to have to avoid using this as it’s causing too many problems.

Could you replicating this and let me know how it behaves (I assume based on your previous post it’ll be fine but it’d be a useful information) you might need to load it a few times and possibly try from an private browsing window.

To me this seems to be a ZS issue but I don’t think they want to accept that at the moment.

I’ve replicated on 3 different builds of Windows with one of those being a non-corporate build.

(Tony Odonnell) #4

Are you using Tunnel forwarding with packet filter driver?

(David Creedy) #5

Tony, can you reference the ticket # here so I can follow up with Engineering on this?

(Tony Odonnell) #6


The ticket is 633252 and this has apparenlty been identified as a bug which has been assigned reference: BUG-42313.
We have been recommended to change our forwarding method to ‘tunnel with local pac file’. I did this and ran it with a few users for a week and when i migrated another 30 people onto it we experienced intermittent outages to internet browsing.
We are still trying to roll out ZS but it’s not going well so far

(David Creedy) #7


Looping back, it’s definitely related to using Tunnel mode + System Proxy causing this. There’s a fundamental difference in how Z App behaves in tunnel mode (pure traffic routing) and tunnel with local proxy (behaves like a local proxy server)

How is the change to Tunnel with Local Proxy going? Have you hit any limitations which are stopping this so far?

(Alex Fray) #8

Hi Tony,

I experienced the google 404 error when using Zapp in tunnel mode. I changed the forwarding mode to tunnel with local proxy and have not seen the error again and it hasn’t been reported by any users. We have over 1000 users running in this mode.

Note. I have had reports of the google 404 error on our Citrix environment where we are using just PAC file to forward traffic (no tunnels or Zapp). So unsure if its just a Zapp issue.