diff --git a/aleph_message/exceptions.py b/aleph_message/exceptions.py
index c8f7873..de043c3 100644
--- a/aleph_message/exceptions.py
+++ b/aleph_message/exceptions.py
@@ -1,2 +1 @@
-class UnknownHashError(ValueError):
-    ...
+class UnknownHashError(ValueError): ...
diff --git a/aleph_message/models/__init__.py b/aleph_message/models/__init__.py
index 4f15e42..3c6e7d0 100644
--- a/aleph_message/models/__init__.py
+++ b/aleph_message/models/__init__.py
@@ -6,14 +6,14 @@
 from pathlib import Path
 from typing import Any, Dict, List, Literal, Optional, Type, TypeVar, Union, cast
 
-from pydantic import BaseModel, Extra, Field, validator
+from pydantic import BaseModel, Field, validator
 from typing_extensions import TypeAlias
 
 from .abstract import BaseContent
 from .base import Chain, HashType, MessageType
+from .execution.base import MachineType, Payment, PaymentType  # noqa
 from .execution.instance import InstanceContent
 from .execution.program import ProgramContent
-from .execution.base import PaymentType, MachineType, Payment  # noqa
 from .item_hash import ItemHash, ItemType
 
 
@@ -22,9 +22,6 @@ class MongodbId(BaseModel):
 
     oid: str = Field(alias="$oid")
 
-    class Config:
-        extra = Extra.forbid
-
 
 class ChainRef(BaseModel):
     """Some POST messages have a 'ref' field referencing other content"""
@@ -44,9 +41,6 @@ class MessageConfirmationHash(BaseModel):
     binary: str = Field(alias="$binary")
     type: str = Field(alias="$type")
 
-    class Config:
-        extra = Extra.forbid
-
 
 class MessageConfirmation(BaseModel):
     """Format of the result when a message has been confirmed on a blockchain"""
@@ -61,16 +55,10 @@ class MessageConfirmation(BaseModel):
         default=None, description="The address that published the transaction."
     )
 
-    class Config:
-        extra = Extra.forbid
-
 
 class AggregateContentKey(BaseModel):
     name: str
 
-    class Config:
-        extra = Extra.forbid
-
 
 class PostContent(BaseContent):
     """Content of a POST message"""
@@ -92,9 +80,6 @@ def check_type(cls, v, values):
                 raise ValueError("A 'ref' is required for POST type 'amend'")
         return v
 
-    class Config:
-        extra = Extra.forbid
-
 
 class AggregateContent(BaseContent):
     """Content of an AGGREGATE message"""
@@ -104,9 +89,6 @@ class AggregateContent(BaseContent):
     )
     content: Dict = Field(description="The content of an aggregate must be a dict")
 
-    class Config:
-        extra = Extra.forbid
-
 
 class StoreContent(BaseContent):
     """Content of a STORE message"""
@@ -118,9 +100,6 @@ class StoreContent(BaseContent):
     ref: Optional[str] = None
     metadata: Optional[Dict[str, Any]] = Field(description="Metadata of the VM")
 
-    class Config:
-        extra = Extra.allow
-
 
 class ForgetContent(BaseContent):
     """Content of a FORGET message"""
@@ -238,7 +217,6 @@ def convert_float_to_datetime(cls, v, values):
         return v
 
     class Config:
-        extra = Extra.forbid
         exclude = {"id_", "_id"}
 
 
@@ -403,6 +381,3 @@ class MessagesResponse(BaseModel):
     pagination_total: int
     pagination_per_page: int
     pagination_item: str
-
-    class Config:
-        extra = Extra.forbid
diff --git a/aleph_message/models/abstract.py b/aleph_message/models/abstract.py
index f272dbd..1882f01 100644
--- a/aleph_message/models/abstract.py
+++ b/aleph_message/models/abstract.py
@@ -1,4 +1,4 @@
-from pydantic import BaseModel, Extra
+from pydantic import BaseModel
 
 
 def hashable(obj):
@@ -23,6 +23,3 @@ class BaseContent(BaseModel):
 
     address: str
     time: float
-
-    class Config:
-        extra = Extra.forbid
diff --git a/aleph_message/models/execution/abstract.py b/aleph_message/models/execution/abstract.py
index 833ba7c..c6271b5 100644
--- a/aleph_message/models/execution/abstract.py
+++ b/aleph_message/models/execution/abstract.py
@@ -5,14 +5,10 @@
 
 from pydantic import Field
 
-from .environment import (
-    FunctionEnvironment,
-    HostRequirements,
-    MachineResources,
-)
+from ..abstract import BaseContent, HashableModel
 from .base import Payment
+from .environment import FunctionEnvironment, HostRequirements, MachineResources
 from .volume import MachineVolume
-from ..abstract import BaseContent, HashableModel
 
 
 class BaseExecutableContent(HashableModel, BaseContent, ABC):
diff --git a/aleph_message/models/execution/environment.py b/aleph_message/models/execution/environment.py
index 1e97073..8e34ed0 100644
--- a/aleph_message/models/execution/environment.py
+++ b/aleph_message/models/execution/environment.py
@@ -28,9 +28,6 @@ class FunctionTriggers(HashableModel):
         description="Persist the execution of the program instead of running it on demand.",
     )
 
-    class Config:
-        extra = Extra.forbid
-
 
 class NetworkProtocol(str, Enum):
     tcp = "tcp"
@@ -78,9 +75,6 @@ class CpuProperties(HashableModel):
         default=None, description="CPU vendor. Allows other vendors."
     )
 
-    class Config:
-        extra = Extra.forbid
-
 
 class HypervisorType(str, Enum):
     qemu = "qemu"
@@ -101,9 +95,6 @@ class NodeRequirements(HashableModel):
         default=None, description="Node address must match this regular expression"
     )
 
-    class Config:
-        extra = Extra.forbid
-
 
 class HostRequirements(HashableModel):
     cpu: Optional[CpuProperties] = Field(
diff --git a/aleph_message/models/execution/volume.py b/aleph_message/models/execution/volume.py
index 0fd0c9e..5fbe9b7 100644
--- a/aleph_message/models/execution/volume.py
+++ b/aleph_message/models/execution/volume.py
@@ -16,10 +16,11 @@ class AbstractVolume(HashableModel, ABC):
     mount: Optional[str] = None
 
     @abstractmethod
-    def is_read_only(self):
-        ...
+    def is_read_only(self): ...
 
     class Config:
+        # This is the only type where we really need to forbid extra fields.
+        # Otherwise the pydantic_encoder will take the first allowed type instead of the correct one.
         extra = Extra.forbid