“undefined” randomly appended in 1% of requested urls on my website since 12 june 2012

Question

Since 12 june 2012 11:20 TU, I see very weirds errors in my varnish/apache logs.

Sometimes, when an user has requested one page, several seconds later I see a simila

Answer 1

Some facts that have been established, especially in this thread: http://productforums.google.com/forum/#!msg/chrome/G1snYHaHSOc/p8RLCohxz2kJ

it happens on pages that have no javascript at all. this proves that it is not an on-page programming error

the user is unaware of the issue and continues to browse quite happily.

it happens a few seconds after the person visits the page.

it doesn't happen to everybody.

happens on multiple browsers (Chrome, IE, Firefox, Mobile Safari, Opera)

happens on multiple operating systems (Linux, Android, NT)

happens on multiple web servers (IIS, Nginx, Apache)

I have one case of googlebot following the link and claiming the same referrer. They may just be trying to be clever and the browser communicated it to the mothership who then set out a bot to investigate.

I am fairly convinced by the proposal that it is caused by plugins. Complitly is one, but that doesn't support Opera. There many be others.

Though the mobile browsers weigh against the plugin theory.

Sysadmins have reported a major drop off by adding some javascript on the page to trick Complitly into thinking it is already initialized.

Here's my solution for nginx:

location ~ undefined/?$  {
  return 204;
}

This returns "yeah okay, but no content for you".

If you are on website.com/some/page and you (somehow) navigate to website.com/some/page/undefined the browser will show the URL as changed but will not even do a page reload. The previous page will stay as it was in the window.

If for some reason this is something experienced by users then they will have a clean noop experience and it will not disturb whatever they were doing.