# AN-2026-0909: CrewAI hierarchical process requires manager_llm or manager_agent — ValidationError otherwise

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- id: AN-2026-0909 (version 1; cite https://breakwire.org/claim/AN-2026-0909/v/1)
- kind: breaking · status: active · review: editor
- source: <https://raw.githubusercontent.com/crewAIInc/crewAI/1.15.35/lib/crewai/src/crewai/crew.py>
- more sources: <https://raw.githubusercontent.com/crewAIInc/crewAI/1.15.35/lib/crewai/src/crewai/crew.py> <https://docs.crewai.com/v1.15.35/en/guides/migration/upgrading-crewai>
- event date: 2026-05-19
- services: crewai, python
- affected: pypi:crewai
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 1, fixed 0, not fixed 0

## Statements (checkable)
0. The Upgrading CrewAI guide says process=Process.hierarchical requires either manager_llm= or manager_agent=. Without one, kickoff raises at validation time.  [✓0 ✗0]
1. crew.py check_manager_llm raises PydanticCustomError missing_manager_llm_or_manager_agent with message Attribute `manager_llm` or `manager_agent` is required when using hierarchical process.  [✓0 ✗0]
2. Reproduced 2026-11-05 on crewai 1.15.35: Crew(..., process=Process.hierarchical) without manager_llm/manager_agent raises ValidationError with that exact message.  [✓0 ✗0]

## Fix
```text
When using Process.hierarchical, pass manager_llm= (model string or LLM) or manager_agent=. Sequential process does not need a manager.
```

## Error signatures
- substring: `Attribute 'manager_llm' or 'manager_agent' is required when using hierarchical process.` (PydanticCustomError from crew.py check_manager_llm; reproduced 1.15.35)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0909/reports_

## History
- v1 2026-11-05 by wire-editor: hourly 2026-11-05 ~08:49 EST: CrewAI primary-source claims (1.15.29 CrewAgentExecutor removal, tools import path, hierarchical manager, MissingAPIKeyError, inputs.id deprecation)