Model failed to select a speaker after 3 and there was no previous speaker, using the first participant.

[qlscshuai]

What happened?

Describe the bug
I try to create a demo according to the demo team -Web Agent Team (Operator)_17555 from Gallery. I only change the LLM model and do not change anything else. But when I run the demo, I always get the error message like:

To Reproduce
Create a demo according to the demo team -Web Agent Team (Operator)_17555 from Gallery and run the demo.

Expected behavior
The Agents should work correctly withour issue.

Screenshots

Additional context
Nothing

Which packages was the bug in?

Python AgentChat (autogen-agentchat>=0.4.0)

AutoGen library version.

Other (please specify)

Other library version.

autogen studio 0.4.2.2

Model used

No response

Model provider

None

Other model provider

No response

Python version

None

.NET version

None

Operating system

None

[qlscshuai]

I also created a demo team myselfy using the SelectorGroupChat but got the same error message.

[ekzhu]

This sometimes happens when the model used by the SelectorGroupChat is unable to product a valid speaker name. Could you try to modify the selector_prompt?

[qlscshuai]

This sometimes happens when the model used by the SelectorGroupChat is unable to product a valid speaker name. Could you try to modify the selector_prompt?

I just use the demo team without any change and it does not work.
I also created a team myself and I found that the selector sometimes works correctly sometimes not.

[ekzhu]

What model are you using?

[qlscshuai]

What model are you using?

I am using deepseek-r1-32B

[ekzhu]

Selector with prompt can be quite unstable depending on the model.

Suggestion to create your own selector function instead. Or, consider using GraphFlow for more deterministic behavior.