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unknown tag 28 encountered error when query Webex REST API


We have followed the steps and created an integration for ServiceNow (

We can get OAuth tokens successfully in ServiceNow.

However, when try to query Webex REST API, there is an error:
"Request not sent to uri= org.apache.commons.httpclient.HttpException: unknown tag 28 encountered"

What's the possible issue here?

3 Replies 3

Santosh Patil
Cisco Employee
Cisco Employee

Is this issue is only with the queuestat API or other API's too a similar issue?
I see queuestat API on ANZ looks good to me.
Eg: curl --location --request GET '' \
--header 'Authorization: Bearer <THE_ACCESS_TOKEN>'

Could you plz provide more to replicate?




Hi Santosh,

Thanks very much for your response.
ServiceNow Support Technician suggested "The "unknown tag 28 encountered" error is because something unexpected came back when trying to establish a TLS connection. The reason that a TLS connection couldn't be established is the HTTP 503 (service unavailable) response from the endpoint server."

Besides creating the integration and using the client id and client secret to get access token, is there any security setting we need to unlock in Webex to allow ServiceNow call the API?

@cynthiachen111  what is the expectation from the client? why is an unknown tag encountered?

Essentially, if it works inside of Postman, any other HTTPS clients, then we need to understand what the ServiceNow HTTPS client expects and why it is failing.

Providing this information to our teams would help.

Also, what is the use case - are you using ServiceNow to ingest WebexCC data? could you share some screenshots so we could try to reproduce this internally? We have ServiceNow developer instances to attempt a similar integration.


Thanks & Regards,


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