Si tienes una app de FastAPI antigua, podrías estar usando Pydantic versión 1.

FastAPI ha tenido compatibilidad con Pydantic v1 o v2 desde la versión 0.100.0.

Si tenías instalado Pydantic v2, lo usaba. Si en cambio tenías Pydantic v1, usaba ese.

///

### Pydantic v1 e v2 na mesma aplicação { #pydantic-v1-and-v2-on-the-same-app }

Não é suportado pelo Pydantic ter um modelo do Pydantic v2 com campos próprios definidos como modelos do Pydantic v1, ou vice-versa.

```mermaid
graph TB
    subgraph "❌ Not Supported"
        direction TB
        subgraph V2["Pydantic v2 Model"]
            V1Field["Pydantic v1 Model"]
        end

from .v2 import BaseConfig as BaseConfig
from .v2 import ModelField as ModelField
from .v2 import PydanticSchemaGenerationError as PydanticSchemaGenerationError
from .v2 import RequiredParam as RequiredParam
from .v2 import Undefined as Undefined
from .v2 import UndefinedType as UndefinedType
from .v2 import Url as Url
from .v2 import Validator as Validator

	VWSUBUVV	X10, V2, V3			// ERROR "expected vector register in vs1 position"
	VWSUBUVX	V1, V2, V3			// ERROR "expected integer register in rs1 position"
	VWADDVV		X10, V2, V3			// ERROR "expected vector register in vs1 position"
	VWADDVX		V1, V2, V3			// ERROR "expected integer register in rs1 position"
	VWSUBVV		X10, V2, V3			// ERROR "expected vector register in vs1 position"

	VDIVESD V1, V2, V3                      // 106113cb
	VDIVESQ V1, V2, V3                      // 1061130b
	VDIVESW V1, V2, V3                      // 1061138b
	VDIVEUD V1, V2, V3                      // 106112cb
	VDIVEUQ V1, V2, V3                      // 1061120b
	VDIVEUW V1, V2, V3                      // 1061128b
	VDIVSD V1, V2, V3                       // 106111cb

        graph.setEntry(v1);
        v2 = graph.addVertex(new ArtifactMetadata("g", "a2", "1.0"));
        v3 = graph.addVertex(new ArtifactMetadata("g", "a3", "1.0"));
        v4 = graph.addVertex(new ArtifactMetadata("g", "a4", "1.0"));

        // v1-->v2
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.1", true, null, null, 2, 1));
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.2", true, null, null, 2, 2));

	VADDUHM V1, V2, V3              // 10611040
	VADDUWM V1, V2, V3              // 10611080
	VADDUDM V1, V2, V3              // 106110c0
	VADDUQM V1, V2, V3              // 10611100
	VADDCUQ V1, V2, V3              // 10611140
	VADDCUW V1, V2, V3              // 10611180
	VADDUBS V1, V2, V3              // 10611200
	VADDUHS V1, V2, V3              // 10611240
	VADDUWS V1, V2, V3              // 10611280

                    }
                    project(":v2") {
                        version = "2.0"
                    }
                """
            )
            withDirectory("v1/src/main").v1()
            withDirectory("v2/src/main").v2()
            val sourceRoots = if (File(withDirectory("v2/src/main"), "java").exists()) {
                "v2/src/main/java"
            } else {

	VPMULL2	V1.H4, V2.H4, V3.Q1                              // ERROR "operand mismatch"
	VPMULL2	V1.D1, V2.D1, V3.Q1                              // ERROR "operand mismatch"
	VPMULL2	V1.B8, V2.B8, V3.H8                              // ERROR "operand mismatch"
	VEXT	$8, V1.B16, V2.B8, V2.B16                        // ERROR "invalid arrangement"
	VEXT	$8, V1.H8, V2.H8, V2.H8                          // ERROR "invalid arrangement"

- MinIO exports Prometheus compatible data by default as an authorized endpoint at `/minio/v2/metrics/cluster`. 
- MinIO exports Prometheus compatible data by default which is bucket centric as an authorized endpoint at `/minio/v2/metrics/bucket`.
- MinIO exports Prometheus compatible data by default which is node centric as an authorized endpoint at `/minio/v2/metrics/node`.