chat template not supported

[ParthKarth]

Am using runpod serverless initially with Deepseek R1 from huggingface, then switched to Llama4-scout for testing but I got this error. No issues on the huggingface side, the model is exactly the same as it was.

Output:
{ "delayTime": 48454, "error": "{'object': 'error', 'message': 'Chat template does not exist for this model, you must provide a single string input instead of a list of messages', 'type': 'BadRequestError', 'param': None, 'code': 400}", "executionTime": 254, "id": "2bee8688-4f7e-4d8d-b198-3ad3054f34d8-u2", "status": "FAILED", "workerId": "9sxpstx8jawche" }

Switched back to deepseek-r1 and still getting the same message.
Nothing was changed but there are processes dependent on this.

Here is the input:

{"input": {
"messages": [
{"role": "system", "content": "You are a physics expert."},
{"role": "user", "content": "What is gravity?"}
]
}}
We changed models in the past and this issue never came up. I don't think its a hf model issue.

Also the models support the system/user type of breakdown

[deanq]

@ParthKarth I searched for Chat template does not exist for this model, you must provide a single string input instead of a list of messages on https://huggingface.co/datasets/PharynxAI/Runpod_VLLM_model_0.1/commit/ce587a512bafcb239e771267b6789282c9456c11 and found this code

def apply_chat_template(self, input: Union[str, list[dict[str, str]]]) -> str:
  if isinstance(input, list):
    if not self.has_chat_template:
      raise ValueError(
        "Chat template does not exist for this model, you must provide a single string input instead of a list of messages"
      )
  elif isinstance(input, str):
    input = [{"role": "user", "content": input}]
  else:
    raise ValueError("Input must be a string or a list of messages")
...

...can you debug and see what input looks like before it raises ValueError?

[kowshik24]

@deanq are you working on this issue? If not can I be assigned in this issue?

[deanq]

There's not much for me to work on. This error is coming from your code. I'm just trying to investigate what you're seeing on your end to help figure it out.

[ParthKarth]

Its not the code. The issues occurred while testing using the UI. The only code is the input body. [cid:e5a6c73c-cd86-47c8-89ce-4bb03fc8b3fc]

…

________________________________ From: Dean Quiñanola ***@***.***> Sent: Sunday, July 27, 2025 10:01 PM To: runpod/runpod-python ***@***.***> Cc: Partha Karthikeyan ***@***.***>; Mention ***@***.***> Subject: Re: [runpod/runpod-python] chat template not supported (Issue #449) [https://avatars.githubusercontent.com/u/1141368?s=20&v=4]deanq left a comment (runpod/runpod-python#449)<#449 (comment)> There's not much for me to work on. This error is coming from your code. I'm just trying to investigate what you're seeing on your end to help figure it out. — Reply to this email directly, view it on GitHub<#449 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/APGJK4QMUVK3GVFANNTWC7L3KWHAFAVCNFSM6AAAAACCEXQ642VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCMRVGE3DANJRGU>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[deanq]

@ParthKarth I can only help up to what I know. Right now. I know you have an error "Chat template does not exist for this model, you must provide a single string input instead of a list of messages". We don't have that anywhere in our code. It does exist somewhere I pointed out in my comment. So I asked, can you debug and see what input looked like when you get that error?

[deanq]

@ParthKarth I will close this since this is user error. The message key requires a single string, not an array of values like you have it. It says Chat template does not exist for this model, you must provide a single string input instead of a list of messages'

Your input messages is a list of dictionaries. Whatever you are trying to do only accepts a string:

{
  "input": {
    "messages": [
      {"role": "system", "content": "You are a physics expert."},
      {"role": "user", "content": "What is gravity?"}
    ]
  }
}