ReGeX patterns compatibility issue with iOS 16

[MMazzari]

Hi,
we would like to know where the dist.js file inside RichMessageRenderer is built, since there might be a compatibility issue with ReGeX patterns inside of it with iOS 16 as we get the following error and we need to fix it:

SyntaxError: Invalid regular expression: invalid group specifier name f (anonymous function) amazon-connect-chat-interface.js:2

EDIT: it seems to me that the error is return by an NPM package called "acorn", but I don't understand where it is used.

Thank you for your help

[agarwhi]

Hello ,

RichMessageRenderer is from an internal dependency and using draftJs.

Looking for following details to dig deep into the issue:

1. What is the current behavior of the widget? How is it performing/functioning? Is the widget crashing on launch or on using richTextEditor?
2. Is this problem specifically occurring on iOS 16, or has it been observed on other iOS versions or operating systems? Are you using webview ? If no, which browser the widget is running ?
3. Please provide detailed step-by-step instructions to reproduce this issue

Thanks,

[mattiamazzari]

Hi, sorry for the delay in the response.
We have contacted the AWS Support Team and have been investigating for 2 weeks. I report briefly the history of the case and our tests:

Description of the problem

We are encountering an issue where the AWS Connect Communication Widget fails to load correctly on iOS devices running iOS 16.1.1 or any version below 16.4 when embedded inside a native iOS WebView. The chatbot initially shows a loading spinner but then ends up displaying a completely blank white screen page (about:blank).

The issue occurs in the native iOS WebView, which uses the default WebKit engine, and not specifically with the Flutter WebView component — in fact, the problem reproduces even with minimal native iOS WebViews or third-party WebView testing apps like "Webview Tester" or "Dodo Webview" from the App Store.

Steps to Reproduce:

• Use a native iOS WebView on an iPhone or an emulator running iOS 16.1.1 or any version below 16.4. We have used "Dodo Webview" on iOS 16.1.1.
• Load a chatbot using the default AWS communication widget script (the out-of-the-box script provided by AWS, without any customization).
• Observe that the chatbot starts loading but then gets stuck on a white screen and eventually the WebView redirects to a blank page. This has been solved with the workaround of disabling the CSM proposed by the AWS Support Team as described in the following only with the default snippet copied from Amazon Connect

Actual Result:

• The chatbot does not fully load and remains on a blank white screen after the loading spinner, eventually redirecting the WebView to an empty page.

Expected Result:

• The chatbot loads successfully and displays the chat interface with messages.

Additional Details:

The issue is reproducible on native iOS WebViews independently of the app implementation or any Flutter integration.
The problem occurs on iOS versions below 16.4 after partial loading, where the WebView crashes or navigates to a blank page.
This strongly suggests the problem lies within the amazon-connect-chat-interface-client.js or other referenced minified JavaScript files provided by AWS, but we have been unable to identify the exact error or incompatibility causing this behavior.
The about:blank pages are created only for versions of iOS < 16.4, as if the communication widget goes to a fallback blank page for something that is not supported inside amazon-connect-chat-interface-client.js
The incompatibility issue may be in some ReGeX, includes() method or CSS properties inside this file (amazon-connect-chat-interface-client.js), we have tried to replace "includes()" with "indexOf() != -1" but nothing has changed.

I attach a video that shows the problem.

Screen.Recording.2025-07-11.at.09.30.53.1.mov

We contacted the AWS Support Team. I report also the questions they asked to us and our answers in the following:

Questions from the AWS Support Team

Q: Are these the only versions of iOS that are affected, or have you tested with iOS versions higher than 16.4
A: We have tested iOS versions higher than 16.4 and everything works fine. We noticed in general that several about:blank pages are created.

Q: Which browser and browser version are you using when you open the communication widget using Dodo Webview
A: We cannot really tell which version is used since we use emulators to test the communication widget with several devices and we cannot verify this point

Test with the AWS Support Team

We have also tested with a basic amplify app created by the AWS Support Team with an Amazon Connect communication widget pointing to an instance in their account. The flow associated with the communication widget is also a simple flow for testing purposes to just to see if the flow can be entered, or if it returns a blank white screen. We encountered the same issue and I attach another video:

Screen.Recording.2025-07-15.at.12.31.57.2.mov

Feedback From Amazon Connect Internal Team And Suggested Workaround

The internal team has confirmed that this issue has been observed on certain older versions of iOS, where the use of SharedWorker causes compatibility problems - particularly in environments like WKWebView. In the Amazon Connect Chat widget, SharedWorker is used to publish client-side metrics (CSM). They have also shared that in order to work around this issue, you can disable CSM for affected iOS versions by adding the following configuration before initializing the widget:

amazon_connect('disableCSM', true);

This prevents the widget from using SharedWorker and should resolve the issue. They also provided some resources where similar iOS behavior has been discussed [1] [2] [3].

Testing of the workaround

✅ Simple OOB widget without amazon-connect-chat-interface.js: The fix works correctly. The basic Amazon Connect Chat widget initializes properly on the affected iOS versions without the SharedWorker compatibility issues.
❌ Custom implementation with "amazon-connect-chat-interface.js": Unfortunately, our chatbot implementation that uses a custom Amazon Connect chat interface with minified embedded frontend customizations is still unable to initialize the session. This appears to be maybe a different issue from the original SharedWorker problem.

The custom implementation now fails during session initialization, which suggests there may be additional compatibility concerns beyond the CSM/SharedWorker issue that was resolved.

I have attached some screenshots about:

• Stack trace information from the failed initialization attempts
• Console logging output that we captured during our debugging process
• Error details specific to our custom interface implementation

Reference

[1] https://github.com/react-native-webview/react-native-webview/issues/2718
[2] https://developer.apple.com/forums/thread/718757
[3] https://stackoverflow.com/questions/74203942/wkwebview-is-not-responding-in-ios-16-1-live-application-is-not-loading-the-con

Thank you for your support,
Mattia