[Studio Flow] Always return 400 code at the end of the flow

[kkday-kevinhorasia]

Using any voice widget from studio flow will always give me error message [We are sorry, an application error has occur] at the end. But if I use my make-call function in studio flow, it will not give me any error.

Possible cause:

1. Free account vs Paid account? (already try both)
2. Wrong constant setting? (already check multiple times)
3. Studio flow bug? (tried with Twilio Client in TwiML App with no problem)

Assumption:

1. Some bug in twilio_voice package, since using native android and ios SDK from twilio doesn't give me that problem

Any idea or possible solution to this problem? Thanks.

[cybex-dev]

HI @kkday-kevinhorasia

Thanks for reporting this issue.

I'm unfamiliar with Studio Flow - do you have a link to the platform I might further investigate the issue with?

[kkday-kevinhorasia]

Unfortunately due to confidential issue I can't share the link. But I will describe it more detail here

Steps:

1. Inside Studio Flow I use [Connect Call To] widget, as the name suggest it connects incoming call to callee.
2. Then I put Studio Flow [Webhook URL] in my TwiML App (instead of function service - make-call).
3. Lastly, in Flutter using TwilioVoice.instance.call.place() to make a call to my TwiML App which connect to my Studio Flow.

[cybex-dev]

@kkday-kevinhorasia sorry, I wasn't clear.

I'm unfamiliar with the Studio Flow platform, my best guess is https://flutterflow.io/ since "Studio Flow" didn't seem to show any results.

Do you have a link to the platform e.g. facebook.com. I understand, respect and do not need access to your account on the platform.

[kkday-kevinhorasia]

Sorry, I mean In Twilio Console Studio Flow.

[cybex-dev]

@kkday-kevinhorasia

I see, thanks for reporting this issue - I'll be investigating over the weekend.

[cybex-dev]

@kkday-kevinhorasia

If you've found a solution in the interim, that's fantastic. If not, I'd like to offer a few suggestions:

Review your TwiML application's code:

• The parameters sent from twilio_voice, in my experience, might be the cause (they might use lower case)

  {
  "To": "...",
  "From": "...",
  }

  This is a remenant from the old twilio_voice I've carrier over, with the intention of changing in future.

• Consider reviewing the calling endpoint e.g. /makeCall as this might not be found
• As a last resort, update your TwiML app with debug output to review request parameters to give further clarity on what's causing the issue. "We are sorry, an application error has occur" is usually a catch-all error message for something akin to 500/Internal Server Error (or along those lines)

[kkday-kevinhorasia]

Thanks for the reply. I will give a simple example that give me that error:

1. In my TwiML app request url link to my Studio Flow.
2. Inside my Studio Flow connect incoming call to Say widget as in the picture below

3. From my Flutter App make call to my TwiML App (which redirect to my Studio Flow)

   TwilioVoice.instance.call.place(
     from: caller, // My own identity
     to: callee, // any (since it will only hear message only)
     extraOptions: extraOptions,
   );

4. I will hear the message from my Studio Flow, but I will also hear the error message "We are sorry, an application error has occur". The execution also will not stop properly and it return 400 error code as we can see from the picture below

[cybex-dev]

Thanks for the reply. I will give a simple example that give me that error:

1. In my TwiML app request url link to my Studio Flow.
2. Inside my Studio Flow connect incoming call to Say widget as in the picture below

3. From my Flutter App make call to my TwiML App (which redirect to my Studio Flow)

TwilioVoice.instance.call.place(
      from: caller, // My own identity
      to: callee, // any (since it will only hear message only)
      extraOptions: extraOptions,
);

4. I will hear the message from my Studio Flow, but I will also hear the error message "We are sorry, an application error has occur". The execution also will not stop properly and it return 400 error code as we can see from the picture below

Might I recommend obfuscating some details

First thoughts, To field is empty - does the same occur with a valid client provided?

[kkday-kevinhorasia]

Yes, with valid client provided (call is connected to callee), the To field at the first flow will have value, but as the flow goes to the second widget the To parameter will be empty.

This behavior also occur when I am calling from Twilio Client in TwiML App, but calling from Twilio Client will not give me any error and the flow end normally.

[cybex-dev]

Yes, with valid client provided (call is connected to callee), the To field at the first flow will have value, but as the flow goes to the second widget the To parameter will be empty.

This behavior also occur when I am calling from Twilio Client in TwiML App, but calling from Twilio Client will not give me any error and the flow end normally.

I see - we're using call flows but haven't run into this problem. I'll need to investigate.

Though, the audible message "An application error has occurred" usually indicates a TwiML (or related) issue.

[kkday-kevinhorasia]

Hi @cybex-dev, I just wondering maybe the problem is caused by not up to date dependencies?

[kkday-kevinhorasia]

UPDATED

The problem is actually from the Twilio Android and iOS SDK and not this package. It seems that Twilio team already fix it.

Twilio reference ticket: # 14617521