article Browser monitors: Missing XHR actions for third-party iframes in Troubleshooting

Browser monitors: Missing XHR actions for third-party iframes

nandini_balakri — Mon, 20 Oct 2025 15:17:13 GMT

Summary

In transitioning the Dynatrace Synthetic Recorder to MV3, JavaScript injection is now based on the Fetch API protocol.

If you've enabled Capture performance metrics for pages loaded in frames in the Advanced setup of browser monitor settings, you might notice that XHR actions for third-party iframes (iframes loading domains other than the main domain) don't show up in the waterfall. This article explains the extra step now needed.

Extra step to see missing XHR actions from third-party frames

To capture XHR actions from third-party iframes, enable disable-site-isolation-trials in chromiumStartupFlags in browser monitor script mode—see the code snippet below. (The default value of disable-site-isolation-trials is false.) Read more about this flag in Chromium documentation.

Important: When you enable the disable-site-isolation-trials flag, be sure not to overwrite any other flags in chromiumStartupFlags (for example, disable-web-security or ignore-certificate-errors), but you can change their values.

{
    "configuration": {
        "chromiumStartupFlags": {
            "disable-web-security": false,
            "disable-site-isolation-trials": true
        },

Refer to Dynatrace Synthetic Monitoring documentation for more information.

What's Next

If the steps didn't resolve the issue, open a chat and provide a link to the browser monitor and the troubleshooting steps you have already completed.

You can find further troubleshooting tips for Synthetic in the Synthetic Troubleshooting Map

Re: Browser monitors: Missing XHR actions for third-party iframes

thecutch22 — Tue, 30 Jan 2024 18:55:03 GMT

The following flag is by default appearing in all scripts in my environment: "disable-web-security": false ... I assume this is why this fix still doesn't work for me, because it is overwriting.

Even when I try to manually remove this flag from a script, it immediately gets added back in. How would I stop that flag from automatically being added?

Thank you!

Re: Browser monitors: Missing XHR actions for third-party iframes

HannahM — Wed, 31 Jan 2024 16:28:27 GMT

@thecutch22 you need to have both, please try

{ "configuration": { "chromiumStartupFlags": { "disable-site-isolation-trials": true, "disable-web-security": false },

If you want to enable disable-web-security instead, you should use "

disable-web-security": true

Re: Browser monitors: Missing XHR actions for third-party iframes

GerardoAud — Fri, 28 Jun 2024 09:15:08 GMT

Hi @HannahM,
I am facing similar issue. Sometimes I noticed that on this steps I do not have full waterfall.

Over the past week, I observed that the waterfall data was fully captured only once, as shown below:

However, for other similar runs during the same period, the waterfall data was missing, as illustrated here:

I would appreciate any insights or recommendations on how to resolve this issue. Are there specific configurations or conditions that could be affecting the consistent capture of waterfall data?

Thanks in advance!

Re: Browser monitors: Missing XHR actions for third-party iframes

HannahM — Fri, 28 Jun 2024 09:33:24 GMT

Hi Gerardo,

this is more easily investigated by looking at the monitor itself. I would recommend opening a chat or support ticket for this.

That said, if you have already added the settings on this page, I would try changing the wait for this page. While testing, you could try 'Wait for a specific period time' and maybe set it to 60s. Then you can quickly see if changing the wait strategy would help. I don't recommend leaving it as a time wait, usually wait for a specified element is a better option, as you can then choose an element that you know appears later in the page loading.

You could also check if there is a service worker on the page, you can either open the site in one tab and in the next tab open chrome://inspect/#service-workers which will show you the active service workers, or if you click F12 and open devTools a search for "ngsw" usually reveals if there is one. If there is one, I recommend applying the "dsw=1" custom configuration to disable the service worker, as described here.

It can also be related to the frameworks or JS Agent settings. So you could test each of the settings in Monitor> Edit> Advanced Setup> Enable custom RUM JavaScript Settings and see if any help.

Re: Browser monitors: Missing XHR actions for third-party iframes

GerardoAud — Mon, 01 Jul 2024 09:52:15 GMT

Hi @HannahM

Hi,

Thank you for the detailed advice. I tried the steps you suggested, but I still have the same issue. I can't see the CSS element/image that I should be seeing. You can check the screenshot below for more details.

Re: Browser monitors: Missing XHR actions for third-party iframes

HannahM — Mon, 01 Jul 2024 09:54:24 GMT

That's a shame. Please open a chat to investigate this further. Thanks

Re: Browser monitors: Missing XHR actions for third-party iframes

Jennifer — Tue, 30 Jul 2024 21:10:49 GMT

Is there a way to add these flags to multiple monitors at once via the API or only through JSON script editing? We have many monitored apps using iframe and this would be helpful to add.

Re: Browser monitors: Missing XHR actions for third-party iframes

HannahM — Wed, 31 Jul 2024 10:10:48 GMT

You can use the Synthetic Monitors API to update this.