Loading chunk 692 failed on Firefox 109.0 and Safari 16.2

[ilario-pierbattista]

Description

Starting from 2023-01-30 we started to get the following load error from users with Firefox 109.0 and Safari 16.2 browsers (both desktop and mobile versions).

Loading chunk 692 failed. (error: https://js-agent.newrelic.com/692.215647de-1223.js)

Steps to Reproduce

I didn't manage to reproduce the error. I've tried to use Firefox 109 (on Ubuntu), but it seems to work.
On the other hand, I see a lot of incoming traffic from Firefox 109 browsers that doesn't report a load failure.
It seems to fail randomically.

Expected Behavior

The script load should never fail.

Relevant Logs / Console output

Loading chunk 692 failed.
(error: https://js-agent.newrelic.com/692.215647de-1223.js)

Your Environment

• php NR agent version: 10.5.0.317
• the agent is configured to auto inject the js script

[workato-integration]

https://issues.newrelic.com/browse/NEWRELIC-6637

[patrickhousley]

Morning @ilario-pierbattista and thanks for reporting this issue. With version 1220, the browser agent began using lazy chunked loading making the initial code that has to be injected into the HTML smaller. We have noticed that certain browsers with more restrictive privacy settings like Firefox with Strict privacy control enabled, DuckDuckGo browser, and ad blockers will block the agent from loading the additional JS resources it needs at runtime. This results in the error you are describing.

We are planning to make that message in the browser console more user friendly. We are also looking for feedback on other options for addressing this concern. Please feel free to share your opinions and feedback, we take all feedback very seriously and ensure it feeds into product development at New Relic.

[ilario-pierbattista]

Hello @patrickhousley, thank you for your reply.
I confirm that configuring Firefox in strict privacy mode made me reproduce the load error.

Maybe the lazy chunked loading could be disabled by configuring the agent?

[patrickhousley]

Thanks for the feedback @ilario-pierbattista , that is one of the options we are considering. Below is the size difference in the code that must be injected into the HTML.

With Code Splitting

File Size	File Name
53K	nr-loader-full-1223.min.js
32K	nr-loader-rum-1223.min.js
59K	nr-loader-spa-1223.min.js

Without Code Splitting

File Size	File Name
104K	nr-loader-full-1223.min.js
85K	nr-loader-rum-1223.min.js
110K	nr-loader-spa-1223.min.js

[bartosz-zolynski]

Confirmed for the browser versions mentioned. Also seen on Safari 16.0. As a "bonus", all e2e tests written in Cypress also started to fail across all the different sub-projects. Interestingly enough, we had *.newrelic.com included on the blockHosts list in Cypress config but it didn't prevent tests to fail. Only after removing this domain from blockHosts made tests working again. Not sure what could be the cause of it?

[patrickhousley]

How are you injecting the agent? The agent is usually contained in the HTML file as an inline script. It will then lazy load chunks from our CDN https://js-agent.newrelic.com/. With that blockHosts in place, the agent will not load and will console.error an error like the one in the original post.

With 1223, we resolved an issue where some sites were redefining the global self variable that was breaking the webpack lazy loader. However, we have also noticed that the chunks can be blocked due to browser privacy settings and/or ad blockers. Privacy settings and ad blockers could also block the network requests the agent makes to send the collected data to New Relic.

Please keep in mind that, if the agent lazy chunks are currently being blocked by privacy settings and/or ad blockers, changing to a single agent file (removing the use of lazy loading) could still result in data not being captured due to those network requests being blocked as well.

As an interim solution, we are making a change in 1224 (eta tbd) to capture the chunk load errors and provide a better message to the console. For the long term, we are actively exploring options with regards to the above mentioned privacy settings and ad blocker issue.

[cwli24]

We found where we had internal uncaught Promises that was causing this problem; culprit was introduced in v1223 restructuring. Thank you for the report!

Edit: To be clear, we're just working to silence this error as there's nothing we can practically do at this time to prevent content blockers from nullifying the agent.

[workato-integration]

Work has been completed on this issue.

[smokinjoe]

https://issues.newrelic.com/browse/NEWRELIC-6637

Your cert has expired - I'm trying to determine if this issue is similar to one I'm experiencing when trying to integrate 1.257.0 into my react app but chrome refuses to let me view the page