The latest version 0.19 found that the newly created assistant session on the webpage cannot obtain chat messages through the HTTP API interface during use

[chaijl]

During use, I found that if I create an assistant directly on a webpage and have a conversation chat, there are no problems on the webpage side. However, when I call the session message through the HTTP API, I will return an IndexError ('list index out of range '). But if I create a session through the HTTP API, it is normal to use the API. However, if I chat again on the original session using a webpage and then call the session message through the API, the same error will be reported again. This was not an issue in the previous version. How should I handle this?

[dosubot[bot]]

This IndexError is caused by a mismatch between the internal data structures for messages and references in a conversation session. When a session is created or updated via the web UI, the structure of the message and reference arrays can diverge from what the HTTP API expects. The API code assumes these arrays are tightly aligned and uses hardcoded index calculations, so any drift (like extra or missing elements) can trigger a "list index out of range" error when you access the session via the API. This regression appeared in v0.19 and was not present before, likely due to changes in how sessions are managed or updated between the UI and API layers.

To work around this, ensure that sessions are created and managed consistently through the same interface (either all via API or all via the web UI). If you encounter the error, deleting problematic sessions and recreating them via the API can resolve it in the short term. For a more robust fix, the codebase needs better schema normalization and error handling to keep the message and reference arrays in sync and to avoid unsafe index access. More details and troubleshooting steps are discussed here and the underlying code logic is visible here.

To reply, just mention @dosu.

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[chaijl]

POST /api/v1/chats/{chat_id}/completions
Calling the session interface and then calling the session list interface will also prompt: IndexError ('list index out of range '). It is estimated that the new version of the field has changed and does not match the API interface. We hope it can be fixed as soon as possible.
GET /api/v1/chats/{chat_id}/sessions @dosu

[dosubot[bot]]

The IndexError is caused by a mismatch between the lengths of the message and reference arrays in session data. This happens when sessions are created or updated differently between the web UI and the API, leading to misalignment that the API code isn't designed to handle. There were no explicit schema changes in v0.19, but the system is now more sensitive to this kind of data drift. Until a fix is released, the safest workaround is to manage sessions consistently through either the API or the web UI, not both. If you hit this error, deleting and recreating the problematic session via the API can help. Defensive code and normalization steps are needed in the backend to prevent this in the future. More details and troubleshooting steps are available in this related discussion: IndexError troubleshooting.

To reply, just mention @dosu.

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[ZhenhangTung]

@chaijl could you share screenshots or logs so we can better troubleshooting?

[ZhenhangTung]

related issue? https://github.com/orgs/infiniflow/discussions/8302

[ZhenhangTung]

Which RAGFlow version and sdk version are you using? @chaijl

[chaijl]

The error log is as follows:list index out of range
Traceback (most recent call last):
File “/ragflow/.venv/lib/python3.10/site-packages/flask/app.py”, line 880, in full_dispatch_request
rv = self.dispatch_request()
File “/ragflow/.venv/lib/python3.10/site-packages/flask/app.py”, line 865, in dispatch_request
return self.ensure_sync(self.view_functions
)(**view_args) # type: ignore

File “/ragflow/api/utils/api_utils.py”, line 298, in decorated_function
return func(*args, **kwargs)
File “/ragflow/api/apps/sdk/session.py”, line 470, in list_session
if “chunks” in conv
:
IndexError: list index out of range

I am using the latest version nightly，Because I first used version 0.17, which was compatible with both web and API operations. However, when I rolled back to version 0.18, it became incompatible. As long as the same session assistant in version 0.18 is operated entirely through the API, it still works fine. I can create a new session assistant in web version 1 and test it separately from the session assistant created by the API. However, I cannot use web operations in the API session assistant again, otherwise the same error will occur. Starting from version 0.19, this operation will not work, and even creating a session assistant through the API and then using the API to obtain the session list will result in the same error

[chaijl]

I am using HTTP API instead of Python

[ZhenhangTung]

Ok. Will double check your case internally.