Benj Benj - 10 days ago 9
Javascript Question

307 Redirect when loading analytics.js in Chrome

I'm building a web app and using Google Analytics (analytics.js) for analytics. I recently noticed that analytics aren't working properly in Chrome.

I'm loading analytics using the standard code snippet in a separate module and included via requirejs. I've verified that this script runs as expected and executes the analytics snippet.

When I inspect network traffic in Firefox, I can see that the analytics script is loaded from Google as expected (HTTP 200 response):

enter image description here

However, when I run the exact same page in Chrome, I get an HTTP 307 response pointing to about:blank, and analytics does not run:

enter image description here

However, if I paste the analytics URL directly into the Chrome address bar, the script is found. Any ideas what's going on here, or how to fix it?

Answer

307 Internal Redirect with Non-Authorative-Reason: Delegate indicates that the request was intercepted and modified (redirected) by a Chrome extension via the webRequest or declarative webRequest extension APIs.

You can find out which extension triggered the redirect as follows:

  1. Visit chrome://net-internals/#events
  2. Trigger the request (google analytics, in your case).
  3. Go back to the chrome://net-internals/#events tab and look for a URL_REQUEST matching your request (you can use the searchbox to filter the search).
  4. Click on the entry to show the log at the right side. You will see the extension name, extension ID and other information about the request:
t=7910 [st=0] +REQUEST_ALIVE  [dt=6]
t=7910 [st=0]   +URL_REQUEST_DELEGATE  [dt=5]
t=7910 [st=0]      DELEGATE_INFO  [dt=5]
                   --> delegate_info = "extension [Name of extension]"
t=7915 [st=5]      CHROME_EXTENSION_REDIRECTED_REQUEST
                   --> extension_id = "ebmlimjkpnhckbaejoagnjlgcdhdnjlb"
t=7915 [st=5]   -URL_REQUEST_DELEGATE
t=7915 [st=5]   +URL_REQUEST_START_JOB  [dt=1]
                 --> load_flags = 339804160 (BYPASS_DATA_REDUCTION_PROXY | MAYBE_USER_GESTURE | REPORT_RAW_HEADERS | VERIFY_EV_CERT)
                 --> method = "GET"
                 --> priority = "LOW"
                 --> url = "https://www.google-analytics.com/analytics.js"
t=7915 [st=5]      URL_REQUEST_REDIRECT_JOB
                   --> reason = "Delegate"
t=7915 [st=5]      URL_REQUEST_FAKE_RESPONSE_HEADERS_CREATED
                   --> HTTP/1.1 307 Internal Redirect
                       Location: about:blank
                       Non-Authoritative-Reason: Delegate

In this log sample, an extension with name "[Name of extension]" and extension ID "ebmlimjkpnhckbaejoagnjlgcdhdnjlb" redirected the request. After finding the extension name and/or ID, you can visit chrome://extensions and disable or remove the extension that modified the request.