Share via


Usage of PAC files on Windows 10 1607

Question

Monday, October 3, 2016 7:55 AM | 1 vote

Our organisation requires use of PAC files to customers whom we support.  For many years we have used a single pac file which is served as default document when a URL is browsed to (so the browsers use pac.mycompany.co.uk and actually get served  pac.mycompany.co.uk/myfile.pac ).  This has worked fine for years, but on machines which have upgraded to Windows 10 Anniversary edition (1607) this has stopped working.  If I feed them the full path to the myfile.pac it works fine, but if I just have them on the URL both IE and Edge fail to load the destination page.  Other browsers (chrome etc) work fine when they are set to use the same settings via Internet Options.

The same machines were working fine before the upgrade.

Is this a 'feature' or a bug?

Cheers,

Ash 

All replies (7)

Tuesday, October 4, 2016 1:29 PM | 1 vote

Hi Ash,

The "local" PAC file (i.e. where you use a "file://....." URI/URL) is not supported and has been deprecated.

More information, please read this article:

Understanding Web Proxy Configuration

http://blogs.msdn.com/b/ieinternals/archive/2013/10/11/web-proxy-configuration-and-ie11-changes.aspx

Please remember to mark the replies as an answers if they help and unmark them if they provide no help.
If you have feedback for TechNet Subscriber Support, contact [email protected].


Tuesday, October 4, 2016 1:32 PM | 1 vote

Hi Karen.

We're not using a file:// path - it's a call to http:// pac.mycompany.co.uk/myfile.pac .

Cheers,

Ash


Thursday, October 6, 2016 7:38 AM

Hi Karen.

We're not using a file:// path - it's a call to http:// pac.mycompany.co.uk/myfile.pac .

Cheers,

Ash

Any error message when you use this type URL?

Please reset the hosts file as the following guide:

How can I reset the Hosts file back to the default?

https://support.microsoft.com/en-in/kb/972034

Meanwhile, reset the DNS and IP:

 1. While on the desktop, press WIN + X.
 2. Select Command Prompt (Admin) .
 3. Type ipconfig /release in the command prompt.
 4. Wait a few seconds for a reply that the IP address has been released.
 5. Type ipconfig /renew in the command prompt
 6. Wait a few seconds for a reply that the IP address has been re-established. 
 7. Type ipconfig /flushdns in the command prompt.
 8. Close the command prompt and attempt to make a connection.

Please remember to mark the replies as an answers if they help and unmark them if they provide no help.
If you have feedback for TechNet Subscriber Support, contact [email protected].


Thursday, October 6, 2016 8:24 AM

Hi Karen. No error, simply doesn't use it.

Host file is already default - no lines in there.

Have reset the IP, flushed the DNS - no difference.

nslookup resolves the URL fine.

It's a good one this!


Tuesday, October 11, 2016 8:23 AM

Ash,

Just use the full path for now and submit the feedback in Windows 10 app. This major update bring so much issue. Let's wait for fix release.


Wednesday, May 3, 2017 2:16 AM

I also have same problem.
It works on Win10 1511, but failed on 1607 and 1703.

At last i have to change the PAC url with full path for all computers via group policy.


Tuesday, May 16, 2017 2:18 PM

Have a look at the mime type of the response of the pac file.  If its not "application/x-ns-proxy-autoconfig" then that will explain why and its a difference between TH2 1511 and RS1 1607.  Either correct the mime type or add a ?.pac querystring.