It seems that Mozilla sometimes ignores the proxy settings and accesses the web directly. I use the Junkbuster ad-busting proxy, and have told Mozilla to use HTTP/1.0 to keep Junkbuster (which does not support HTTP/1.1) happy. But in several cases, ads which Junkbuster would block still show up in the browser window. If I then check the Junkbuster logfile, I do not see those ads show up at all. This implies that they were never requested through the proxy. If I then load the same page with Netscape Navigator, using the same proxy settings, the ads are requested through Junkbuster, which blocks them, and the page is pristine and ad-free... I know that Junkbuster has problems with HTTP/1.1, but since I told Mozilla to use only HTTP/1.0 this should not be the problem...

Actually a dup of bug 38488. There is a workaround on that bug. Can you reproduce with the workaround? Thanks, Fabian.

It seems to work when both HTTP Keep-Alive is OFF and HTTP-version is 1.0. Setting HTTP-version to 1.0 itself (as I usually do) is not enough. So the work-around is to set HTTP-version to 1.0, and turn HTTP-Keep-Alive OFF.

i'm not surprised that the keep-alive code would be contributing to this problem. it tries to keep socket transports open... and may incorrectly reuse them when the host:port matches, but the proxy host:port does not! i have to verify how HTTP is selecting socket transports to reuse. investigating...

Marking NEW while we figure this one out. Helps get it off our unconfirmed radar.

*** This bug has been marked as a duplicate of 38488 ***

Verified dupe.