Status codes for errors related Ajax requests in Browser monitoring and Synthetics

While going through the request/responses for one of the synthetic monitoring script, the status for a request was mentioned as “400 Service Worker Fallback Required”. After this error, there was another instance of the same request that was successful with 200 response code. To understand if this is happening for production users, browser monitoring was examined. The same ajax request was shown as having Network error under the “Status code Excluding 200s” section. Can you please help with the below?

  1. The reason for “400 Service Worker Fallback Required” error in Synthetics script
  2. More details on Network error under the “Status code Excluding 200s” section from the browser monitoring
  3. Are the above two related, as the synthetic script has been running continuously as part of our monitoring?

Browser monitoring URL:

https://rpm.newrelic.com/accounts/2099357/browser/179656457/bjax_requests#filter=/subscriptions&id=5b22416a61782f4d6574686f6450617468526571756573742f4745542f6163636f756e742e6f75702e636f6d3a3434332f506174682f6170692f6365732f6f72672f2a2f757365722f2a2f737562736372697074696f6e732f526573706f6e736554696d65222c22225d

Synthetic result URL:

https://synthetics.newrelic.com/accounts/2099357/monitors/13d76d9e-08de-479d-b457-bcd9881bc4b4/results/4b81b8eb-3ed4-40e2-8f04-e087bcecfa8e?view=timeline

Attached are the screenshots for your reference.

StatusCode_BrowserMonitoring

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Hi @VithalKumar.Akunuri1

I’ve never seen that 400 Service Worker Fallback Required error before in Synthetics. I think it’s going to need some further investigation, especially in how it ties to Browser data as you need.

I did find this:
https://chromium.googlesource.com/chromium/src.git/+/62.0.3178.1/content/browser/service_worker/service_worker_url_request_job.cc#849

Which points to that 400 error being somehow related to CORS… but for more assistance I’ll get a ticket created for you - where my colleagues in Support can get you some help.

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Thanks , will wait for inputs and feedback on this issue.

I’m curious to hear what the answer you get is - so do please post back here when you get that ticket closed out :smiley:

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I’m also curious to know if this was solved. Haven’t found much about this anywhere else.

@luis4 Welcome to the community!