Failed to process "L" of JSON value when calling Azure Functions from Azure Logic app.

Question

Failed to process "L" of JSON value when calling Azure Functions from Azure Logic app.

Sohyeon Cho (DHL KR) 36

The Logic app flow I'm creating has steps that call Azure Functions.

Azure Functions is responsible for sending SMS. Call this function from Logic app, SMS is sent well. This means that the request was sent successfully. However, in the Logic app flow, it fails with an error message of BadRequest.

<Logic app Error>

BadRequest. Http request failed: the content was not a valid JSON. Error while parsing JSON: 'Unexpected character encountered while parsing value: L. Path '', line 0, position 0.'

User's image

🔎Can't I use L as JSON Value??? I don't understand, am I not understanding the error correctly?

<Logic app History>

User's image

Content-Type = application/json; charset=utf-8

<Request Body>

{
  "callback": "01012341234",
  "dhlUnit": "HR",
  "dhlUserIp": "127.0.0.1",
  "dhlUserName": "Sohyeon Cho",
  "dstAddr": "01055556666",
  "msgType": "L",
  "subject": "HR Guide",
  "text": "LOGIC APP LMS TEST LOGIC APP LMS TEST LOGIC APP LMS TEST LOGIC APP LMS TEST LOGIC APP LMS TEST LOGIC APP LMS TEST"
}

Pramod Valavala 20,656 Reputation points Microsoft Employee Moderator

2023-07-28T11:08:50.4566667+00:00

@Sohyeon Cho (DHL KR) Could you confirm if the same payloads works when calling your function app directly using Postman or from the Azure Portal?

Also, could you share how you are passing the request body in the action and where it is constructed?
Sohyeon Cho (DHL KR) 36 Reputation points

2023-07-31T00:26:47.4466667+00:00

@Pramod Valavala This is an API that has been verified many times in postman or the Azure Developer portal. Request body is same for all(postman, azure developer portal, logic app) The error occurs only when called from the Logic app.

▼Request body configured in Logic App
Pramod Valavala 20,656 Reputation points Microsoft Employee Moderator

2023-07-31T20:02:54.7533333+00:00

@Sohyeon Cho (DHL KR) Thanks for sharing more information! Based on the screenshot, I believe the problem could be the lack of double quotes (") around the token inserted for the dhlUserName property.

If that doesn't do the trick, please do share the input/output values from a failed run which could shed more light into what is going wrong here.
Sohyeon Cho (DHL KR) 36 Reputation points

2023-08-01T01:47:33.89+00:00
@Pramod Valavala Thank you for the guide but it didn't work. The response of the function app called by the logic app is a plain string. Can this be a problem?

✔️Function app Response header & Body - called from postman

✔️Function app Response source code

let resultComment module.exports = async function (context, req) { .... .... // All required parameters are provided await LmsInsert(req); context.res = { status: httpStatus, headers: { 'Content-Type': 'application/json' }, body: resultComment, }; } };

1 answer

Your answer

Pramod Valavala 20,656 Reputation points Microsoft Employee Moderator

2023-07-28T11:08:50.4566667+00:00

@Sohyeon Cho (DHL KR) Could you confirm if the same payloads works when calling your function app directly using Postman or from the Azure Portal?

Also, could you share how you are passing the request body in the action and where it is constructed?
Sohyeon Cho (DHL KR) 36 Reputation points

2023-07-31T00:26:47.4466667+00:00

@Pramod Valavala This is an API that has been verified many times in postman or the Azure Developer portal. Request body is same for all(postman, azure developer portal, logic app) The error occurs only when called from the Logic app.

▼Request body configured in Logic App
Pramod Valavala 20,656 Reputation points Microsoft Employee Moderator

2023-07-31T20:02:54.7533333+00:00

@Sohyeon Cho (DHL KR) Thanks for sharing more information! Based on the screenshot, I believe the problem could be the lack of double quotes (") around the token inserted for the dhlUserName property.

If that doesn't do the trick, please do share the input/output values from a failed run which could shed more light into what is going wrong here.
Sohyeon Cho (DHL KR) 36 Reputation points

2023-08-01T01:47:33.89+00:00

@Pramod Valavala Thank you for the guide but it didn't work. The response of the function app called by the logic app is a plain string. Can this be a problem?

✔️Function app Response header & Body - called from postman

✔️Function app Response source code

let resultComment module.exports = async function (context, req) { .... .... // All required parameters are provided await LmsInsert(req); context.res = { status: httpStatus, headers: { 'Content-Type': 'application/json' }, body: resultComment, }; } };

Answer 1

Pramod Valavala 20,656 Microsoft Employee Moderator

@Sohyeon Cho (DHL KR) Since the function app response is a string but has a Content-Type value set to application/json, it should ensure the string is enclosed in double quotes (") in the body.

A string value enclosed in double quotes (") is still considered a valid JSON value and should be able to be parsed without error.

Or you could set the Content-Type header value to text/plain in your function app response as well.

Sohyeon Cho (DHL KR) 36 Reputation points

2023-09-15T05:17:32.8066667+00:00

This problem solved by editing function app response body string to json. (Content-Type: application/json)

Thank you for your support.

Share via

Failed to process "L" of JSON value when calling Azure Functions from Azure Logic app.

<Logic app Error>

<Logic app History>

<header>

<Request Body>

1 answer

Your answer