[Bug]: TypeError: cannot create 'types.UnionType' instances

[juliangardin]

Do you need to file an issue?

• I have searched the existing issues and this bug is not already filed.
• I believe this is a legitimate bug, not just a question or feature request.

Describe the bug

 from mcp_agent.elicitation.types import ElicitationCallback  
    

class ElicitRequestParams(MCPElicitRequestParams):
        server_name: str | None = None
        """Name of the MCP server making the elicitation request"""

TypeError: cannot create 'types.UnionType' instances

Steps to reproduce

Follow installation exactly, use Google LLM

Expected Behavior

Streamlit launches without failures

DeepCode Config Used

Paste your config here

llm_provider: "google"  # 设置为 "google", "anthropic", 或 "openai"

openai:
  base_max_tokens: 40000
  default_model: google/gemini-2.5-pro
  # default_model: anthropic/claude-sonnet-4.5
  # default_model: openai/gpt-oss-120b
  # default_model: deepseek/deepseek-v3.2-exp
  # default_model: moonshotai/kimi-k2-thinking
  reasoning_effort: low  # Only for thinking models
  max_tokens_policy: adaptive
  retry_max_tokens: 32768

# Configuration for Google AI (Gemini)
google:
  default_model: "gemini-3-pro-preview"

Logs and screenshots

No response

Additional Information

• DeepCode Version: 1.0.8
• Operating System: Sequoia
• Python Version: 3.13.9
• Related Issues:

[Rybens92]

Right now project absolutely cannot launch because of that error with any current or previous versions.
Can someone suggest what to do, to al least temporary, fix that, please?

[HeronKe]

I got same error.