docs: add OSS upgrade & crew-to-flow migration guide

2026-05-08 02:29:00 +00:00 · 2026-05-07 16:56:41 +00:00
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+---
+title: "Upgrading & Migrating CrewAI"
+description: How to upgrade CrewAI, migrate around breaking changes, and move standalone Crews onto Flows.
+icon: arrow-up-right-dots
+---
+
+## Overview
+
+CrewAI moves quickly. New releases regularly tighten import paths, change defaults on `Agent`, `Crew`, and `Task`, and introduce new orchestration primitives like `Flow` and checkpointing. This guide collects the practical steps needed to:
+
+- Upgrade the `crewai` CLI and your project dependencies
+- Adapt to breaking changes in imports and parameters
+- Migrate a standalone `Crew` to a typed `Flow`
+- Avoid the gotchas that show up the first time you re-run an upgraded project
+
+If you're starting fresh, see [Installation](/en/installation). If you're coming from another framework, see the [migration guides](/en/guides/migration/migrating-from-langgraph).
+
+---
+
+## Upgrading CrewAI
+
+CrewAI is distributed as a `uv` tool. `pip install -U crewai` works in a pinch, but the supported upgrade path is `uv`.
+
+### 1. Check your current version
+
+```bash
+uv tool list
+```
+
+You should see a line like:
+
+```
+crewai v0.102.0
+- crewai
+```
+
+### 2. Upgrade the CLI
+
+```bash
+uv tool install crewai --upgrade
+```
+
+If your shell warns about `PATH` after the upgrade, refresh it:
+
+```bash
+uv tool update-shell
+```
+
+### 3. Verify the upgrade
+
+```bash
+uv tool list
+crewai --version
+```
+
+### 4. Update project dependencies
+
+The CLI upgrade only updates the global tool. Each project pins its own `crewai` dependency in `pyproject.toml`. Inside the project directory, run:
+
+```bash
+crewai install
+```
+
+This re-syncs your project's lockfile and virtual environment against the new version. Run your tests or `crewai run` afterwards to surface any breakage early.
+
+<Note>
+  CrewAI requires `Python >=3.10, <3.14`. If `uv` was installed against an older interpreter, recreate the project venv with a supported Python before running `crewai install`.
+</Note>
+
+---
+
+## Breaking Changes & Migration Notes
+
+Most upgrades only require small adjustments. The areas below are the ones that break silently or with confusing tracebacks.
+
+### Import paths: tools and `BaseTool`
+
+The canonical import location for tools is `crewai.tools`. Older paths still surface in tutorials but should be updated.
+
+```python
+# Before
+from crewai_tools import BaseTool
+from crewai.agents.tools import tool
+
+# After
+from crewai.tools import BaseTool, tool
+```
+
+The `@tool` decorator and `BaseTool` subclass both live in `crewai.tools`. `AgentFinish` and other internal-agent symbols are no longer part of the public surface — if you were importing them, switch to event listeners or `Task` callbacks instead.
+
+### `Agent` parameter changes
+
+```python
+from crewai import Agent
+
+agent = Agent(
+    role="Researcher",
+    goal="Find authoritative sources on {topic}",
+    backstory="You are a careful, source-driven researcher.",
+    llm="gpt-4o-mini",   # string model name OR an LLM object
+    verbose=True,        # bool, not an int level
+    max_iter=15,         # default has changed across versions — set explicitly
+    allow_delegation=False,
+)
+```
+
+- `llm` accepts either a string model name (resolved via the configured provider) or an `LLM` object for fine-grained control.
+- `verbose` is a plain `bool`. Passing an integer no longer toggles log levels.
+- `max_iter` defaults have shifted between releases. If your agent silently stops looping after the first tool call, set `max_iter` explicitly.
+
+### `Crew` parameters
+
+```python
+from crewai import Crew, Process
+
+crew = Crew(
+    agents=[...],
+    tasks=[...],
+    process=Process.sequential,   # or Process.hierarchical
+    memory=True,
+    cache=True,
+    embedder={"provider": "openai", "config": {"model": "text-embedding-3-small"}},
+)
+```
+
+- `process=Process.hierarchical` requires either `manager_llm=` or `manager_agent=`. Without one, kickoff raises at validation time.
+- `memory=True` with a non-default embedding provider needs an `embedder` dict — see [Memory & embedder config](#memory-embedder-config) below.
+
+### `Task` structured output
+
+Use `output_pydantic`, `output_json`, or `output_file` to coerce a task's result into a typed shape:
+
+```python
+from pydantic import BaseModel
+from crewai import Task
+
+class Article(BaseModel):
+    title: str
+    body: str
+
+write = Task(
+    description="Write an article about {topic}",
+    expected_output="A short article with a title and body",
+    agent=writer,
+    output_pydantic=Article,        # the class, NOT an instance
+    output_file="output/article.md",
+)
+```
+
+`output_pydantic` takes the **class** itself. Passing `Article(title="", body="")` is a common mistake and fails with a confusing validation error.
+
+### Memory & embedder config
+
+If `memory=True` and you're not using the default OpenAI embeddings, you must pass an `embedder`:
+
+```python
+crew = Crew(
+    agents=[...],
+    tasks=[...],
+    memory=True,
+    embedder={
+        "provider": "ollama",
+        "config": {"model": "nomic-embed-text"},
+    },
+)
+```
+
+Set the relevant provider credentials (`OPENAI_API_KEY`, `OLLAMA_HOST`, etc.) in your `.env` file. Memory storage paths are project-local by default — delete the project's memory directory if you change embedders, since dimensions don't mix.
+
+---
+
+## Migrating a Crew to a Flow
+
+`Crew` is the right primitive when you have a single team of agents executing one workflow. Once you need branching, multiple crews, or persistent state across runs, reach for `Flow`.
+
+### When to use Flows vs standalone Crews
+
+| Situation | Use |
+| --- | --- |
+| Single team, single linear/hierarchical workflow | `Crew` |
+| Conditional branches, retries, routing on results | `Flow` |
+| Multiple specialized crews chained together | `Flow` |
+| State that must persist between steps or runs | `Flow` (with checkpointing) |
+| You want typed, IDE-friendly state | `Flow[MyState]` with a Pydantic model |
+
+If you only need one of: branching, multi-crew, or persistent state — start with a `Flow`. The boilerplate is small and you won't have to rewrite later.
+
+### Step-by-step migration
+
+**Before — standalone crew:**
+
+```python
+from crewai import Crew
+
+crew = Crew(agents=[researcher, writer], tasks=[research_task, write_task])
+result = crew.kickoff(inputs={"topic": "vector databases"})
+print(result)
+```
+
+**After — crew inside a typed Flow:**
+
+```python
+from crewai.flow.flow import Flow, start, listen
+from pydantic import BaseModel
+
+class MyState(BaseModel):
+    input_data: str = ""
+    result: str = ""
+
+class MyFlow(Flow[MyState]):
+    @start()
+    def run_crew(self):
+        result = MyCrew().crew().kickoff(inputs={"topic": self.state.input_data})
+        self.state.result = str(result)
+        return self.state.result
+
+flow = MyFlow()
+flow.kickoff(inputs={"input_data": "vector databases"})
+```
+
+What changed:
+
+1. The crew is constructed inside a method, not at module load.
+2. Inputs flow through `self.state` instead of being threaded as kwargs.
+3. The entry point is marked with `@start()`. Subsequent steps use `@listen(run_crew)` to chain.
+
+### Structured state setup
+
+Prefer typed state (`Flow[MyState]`) over the untyped dict variant. You get autocompletion, validation at the boundary, and serializable state for checkpointing:
+
+```python
+from pydantic import BaseModel, Field
+
+class ResearchState(BaseModel):
+    topic: str = ""
+    sources: list[str] = Field(default_factory=list)
+    draft: str = ""
+    final: str = ""
+```
+
+Untyped state (`Flow()` with no generic) still works, but you lose static checks and checkpointing fidelity.
+
+### Multi-crew Flow pattern
+
+Chaining two crews — research, then writing — is the canonical reason to adopt Flows:
+
+```python
+from crewai.flow.flow import Flow, start, listen, router
+from pydantic import BaseModel
+
+class PipelineState(BaseModel):
+    topic: str = ""
+    research: str = ""
+    article: str = ""
+
+class ContentPipeline(Flow[PipelineState]):
+    @start()
+    def research(self):
+        out = ResearchCrew().crew().kickoff(inputs={"topic": self.state.topic})
+        self.state.research = str(out)
+        return self.state.research
+
+    @router(research)
+    def gate(self):
+        return "write" if len(self.state.research) > 200 else "abort"
+
+    @listen("write")
+    def write(self):
+        out = WritingCrew().crew().kickoff(
+            inputs={"topic": self.state.topic, "notes": self.state.research}
+        )
+        self.state.article = str(out)
+        return self.state.article
+
+    @listen("abort")
+    def bail(self):
+        self.state.article = "Insufficient research."
+        return self.state.article
+
+ContentPipeline().kickoff(inputs={"topic": "vector databases"})
+```
+
+`@start()`, `@listen()`, and `@router()` are the three decorators you'll use 95% of the time. See [Flows](/en/concepts/flows) for the full reference.
+
+---
+
+## Common Gotchas
+
+1. **`pip install` instead of `uv tool install`.** The CLI is a `uv` tool. Mixing pip-installed and uv-installed `crewai` leads to two binaries on `PATH` and confusing version skew. Pick one — the supported one is `uv`.
+2. **Forgetting `crewai install` after upgrading.** The CLI upgrade is global; your project venv still pins the old version until you re-sync.
+3. **Passing a Pydantic instance to `output_pydantic`.** It expects the class. `output_pydantic=Article`, not `output_pydantic=Article(...)`.
+4. **Hierarchical process with no manager.** `process=Process.hierarchical` requires `manager_llm=` or `manager_agent=`.
+5. **Memory enabled with the wrong embedder.** Switching embedders without clearing the on-disk memory directory causes dimension mismatches. Delete the project's memory store after changing providers.
+6. **Dict state when you wanted typed state.** `Flow()` with no generic gives you a dict. For type checking and clean checkpointing, use `Flow[MyState]` with a `BaseModel`.
+7. **Stale tool imports.** `from crewai_tools import BaseTool` works in some versions but is not the canonical path. Standardize on `from crewai.tools import BaseTool, tool`.
+8. **Python version drift.** CrewAI requires `>=3.10, <3.14`. `uv` will happily build a venv against 3.14+ if it's the default; pin the Python version in `pyproject.toml`.
+9. **`verbose=2` and similar integer flags.** `verbose` is a `bool`. Use event listeners for finer-grained logging.
+10. **Calling `crew.kickoff()` from inside a Flow without wrapping in `inputs={}`.** Flows pass state, not kwargs. The crew still expects `inputs={...}`.
+
+---
+
+## Checkpointing
+
+Checkpointing is a newer addition that persists agent, crew, and flow state between runs. It lets long-running workflows resume after a crash, a manual stop, or a deploy.
+
+```python
+crew = Crew(
+    agents=[...],
+    tasks=[...],
+    checkpoint=True,
+)
+```
+
+The same flag is supported on `Flow` and `Agent`. State is written to the project's local store and replayed on the next `kickoff()` with the same identifier.
+
+<Note>
+  Checkpointing is in early release. APIs around resume semantics, storage backends, and identifiers may still shift between minor versions — pin your `crewai` version if you depend on it in production.
+</Note>
+
+See [Checkpointing](/en/concepts/checkpointing) for the full feature reference.
+
+---
+
+## Getting Help
+
+- **Changelog** — every breaking change is noted in the [release notes](/en/changelog).
+- **GitHub Issues** — open one at [github.com/crewAIInc/crewAI/issues](https://github.com/crewAIInc/crewAI/issues) with a minimal repro and your `crewai --version` output.
+- **Discord** — the CrewAI community Discord is the fastest path to debugging help: [community.crewai.com](https://community.crewai.com).
+- **Migration guides** — if you're moving from another framework, start at [Migrating from LangGraph](/en/guides/migration/migrating-from-langgraph).