Change request summarization in Now Assist Not working in ITSM

[Navinr]

Recently, we enabled Now Assist in ITSM, and all skills were functioning correctly.
We are now facing an issue where Change Request Summarization is not working for one specific change request in PPC.
The behavior is inconsistent, as summaries are sometimes generated in the Review state but consistently generated in the Closed state for same  change requests.
The same scenario works as expected in DEV.

in the sys_generative_ai_log_list  logs  I checked I've got 

Error code :200001
Error :Invalid JSON returned from LLM
Response token count :543

Any help in troubleshooting this issue would be appreciated.

[Dr Atul G- LNG]

Hi @Navinr 

https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB2821601

2. Invalid JSON or LLM Response Errors (Error 200001)

Issue

Summarization fails with the following error: Error Code 200001 – Invalid JSON returned by model

Cause

This error typically occurs due to one of the following conditions:

• Response token limit is too low
• The record contains a large payload (many journal entries)
• A NowLLM model issue affecting specific records

How to Identify the Root Cause

1. Navigate to sys_generative_ai_log.
2. Locate the failed summarization request.
3. Inspect the model_output field.

If the JSON response appears truncated or incomplete, the response exceeded the configured token limit.

1. Open the associated Generative AI Configuration record.
2. Review the Response Max Tokens value.

Resolution

1. Navigate to the Generative AI Configuration used by the summarization skill.
2. Increase Response Max Tokens (example: 1000 or higher).
3. Save the configuration.
4. Re-test summarization.

Recommendation

Whenever prompts are customized to produce longer responses, ensure the token limit is increased accordingly.

Known Platform Issue – Malformed JSON from NowLLM

[Navinr]

Hello @Dr Atul G- LNG Thanks for the  Quick response
but here I'm not able to edit Response max tokens counts all fields are read only  

The response returned 543 tokens, but the configured definition indicates 800 tokens.

[Dr Atul G- LNG]

Hi @Navinr 

I think  case with now support is best .