> ## Documentation Index
> Fetch the complete documentation index at: https://arizeai-433a7140.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Release Notes

> Breaking changes in Phoenix v14.0.0: CLI restructuring, legacy client removal, evaluations endpoint removal, evals 1.0 removal, and GraphQL pagination.

# Breaking Change: CLI Now Subcommand-First

April 7, 2026

**Breaking change in arize-phoenix 14.0.0**

The Phoenix server CLI is now **subcommand-first**. Flags that previously preceded the subcommand must now follow it.

**Before:**

```bash theme={null}
phoenix --dev serve
phoenix --host 0.0.0.0 --port 6006 serve
python -m phoenix.server.main --dev --dev-vite-port 5173 serve
```

**After:**

```bash theme={null}
phoenix serve --dev
phoenix serve --host 0.0.0.0 --port 6006
python -m phoenix.server.main serve --dev --dev-vite-port 5173
```

The `db migrate` subcommand is unchanged. Pass `--database-url` directly to the subcommand that needs it, or rely on `PHOENIX_SQL_DATABASE_URL`:

```bash theme={null}
phoenix serve --database-url "postgresql://..."
phoenix db migrate --database-url "postgresql://..."
```

The deprecated `--enable-websockets` flag has been removed. Use `phoenix serve --help` or `phoenix db migrate --help` for full option listings.

# Breaking Change: Legacy `px.Client()` Removed

April 7, 2026

**Breaking change in arize-phoenix 14.0.0**

`phoenix.session.client.Client` (accessed as `px.Client()`) has been removed. All client interactions now go through `arize-phoenix-client`.

```bash theme={null}
pip install arize-phoenix-client
```

**Before:**

```python theme={null}
import phoenix as px

client = px.Client(endpoint="http://localhost:6006")
spans_df = client.get_spans_dataframe()
```

**After:**

```python theme={null}
from phoenix.client import Client

client = Client(base_url="http://localhost:6006")
spans_df = client.spans.get_spans_dataframe()
```

The `endpoint` parameter is now `base_url`. When omitted, the client falls back to environment variables or `http://localhost:6006`. The new client organizes methods under resource namespaces (`.spans`, `.traces`, `.datasets`, `.experiments`) instead of flat methods on the client object.

See the [v14 migration guide](https://github.com/Arize-ai/phoenix/blob/main/MIGRATION.md) for a full method-by-method mapping.

# Breaking Change: `/v1/evaluations` Endpoint Removed

April 7, 2026

**Breaking change in arize-phoenix 14.0.0**

The `POST /v1/evaluations` and `GET /v1/evaluations` REST endpoints have been removed. Use the annotations API instead:

| Previous                                | Replacement                              |
| :-------------------------------------- | :--------------------------------------- |
| `POST /v1/evaluations` (span evals)     | `POST /v1/span_annotations`              |
| `POST /v1/evaluations` (trace evals)    | `POST /v1/trace_annotations`             |
| `POST /v1/evaluations` (document evals) | `POST /v1/document_annotations`          |
| `GET /v1/evaluations`                   | `client.spans.get_span_annotations(...)` |

**Before:**

```python theme={null}
from phoenix.trace import SpanEvaluations
import phoenix as px

px.Client().log_evaluations(
    SpanEvaluations(eval_name="Hallucination", dataframe=results_df)
)
```

**After:**

```python theme={null}
from phoenix.client import Client

Client().spans.log_span_annotations_dataframe(
    dataframe=results_df,
    annotation_name="Hallucination",
    annotator_kind="LLM",
)
```

`protobuf` is no longer a direct dependency of the Phoenix server (it remains a transitive dependency via OpenTelemetry gRPC packages).

# Breaking Change: Evals 1.0 Removed

April 7, 2026

**Breaking change in arize-phoenix-evals 3.0.0, arize-phoenix-client 2.3.1+**

`arize-phoenix-evals` 3.0.0 removes the legacy evals 1.0 module and the legacy experiments module from the Phoenix server package.

**Removed from `arize-phoenix-evals`:**

* The entire `legacy/` subpackage and its `models/` wrappers
* `MultimodalPrompt`, `PromptPartContentType`, and `PromptPart` types — all adapter methods now use `PromptLike`

**Removed from `arize-phoenix`:**

* `phoenix.experiments` — the legacy experiment execution module (`functions.py`, `tracing.py`, `evaluators/`)
* `phoenix.experiments.types` — use `phoenix.client.__generated__.v1.DatasetExample` instead

**Experiments migration:**

```python theme={null}
# Before
from phoenix.experiments.types import Example
from phoenix.experiments.evaluators import create_evaluator
from phoenix.experiments import run_experiment, evaluate_experiment

experiment = run_experiment(dataset, task, evaluators=[...])

# After
from phoenix.client.__generated__.v1 import DatasetExample as Example
from phoenix.client.experiments import create_evaluator, run_experiment, evaluate_experiment

experiment = run_experiment(dataset=dataset, task=task, evaluators=[...])
```

The `phoenix-client` experiments module (`phoenix.client.experiments`) is the replacement and has no dependency on `arize-phoenix-evals`.

# Breaking Change: GraphQL Forward Pagination Requires `first`

April 7, 2026

**Breaking change in arize-phoenix 14.0.0**

Three GraphQL connection fields now require an explicit `first` argument and no longer accept backward pagination (`last`/`before`):

| Type             | Field    | Max `first` |
| :--------------- | :------- | :---------- |
| `Project`        | `spans`  | 1000        |
| `Trace`          | `spans`  | 1000        |
| `ProjectSession` | `traces` | 1000        |

**Before:**

```graphql theme={null}
query {
  project(id: "...") {
    spans {
      edges { node { name } }
    }
  }
}
```

**After:**

```graphql theme={null}
query {
  project(id: "...") {
    spans(first: 100) {
      edges { node { name } }
    }
  }
}
```

Queries that omit `first` will fail with `"first" is required`. Queries that pass `first` greater than 1000 will fail with `"first" must be less than or equal to 1000`. Backward pagination with `last`/`before` is no longer supported on these fields.

This change protects the server from unbounded queries that could cause excessive memory usage and slow response times.