diff --git a/app/schemas/activity.py b/app/schemas/activity.py
index b0f7ad5..9a10cc7 100644
--- a/app/schemas/activity.py
+++ b/app/schemas/activity.py
@@ -16,5 +16,6 @@ class Activity(ActivityBase):
     id: int
     user_id: int
 
-    class Config:
-        orm_mode = True
\ No newline at end of file
+    model_config = {
+        "from_attributes": True
+    }
\ No newline at end of file
diff --git a/app/schemas/client.py b/app/schemas/client.py
index 962e8b2..7be205c 100644
--- a/app/schemas/client.py
+++ b/app/schemas/client.py
@@ -2,6 +2,9 @@ from typing import List, Optional
 
 from pydantic import BaseModel, EmailStr
 
+# Import at the top level to avoid circular imports
+from app.schemas.invoice import Invoice
+
 
 # Shared properties
 class ClientBase(BaseModel):
@@ -29,8 +32,9 @@ class ClientInDBBase(ClientBase):
     id: int
     user_id: int
 
-    class Config:
-        orm_mode = True
+    model_config = {
+        "from_attributes": True
+    }
 
 
 # Properties to return via API
@@ -45,5 +49,4 @@ class ClientInDB(ClientInDBBase):
 
 # Client with invoices
 class ClientWithInvoices(Client):
-    from app.schemas.invoice import Invoice
     invoices: List[Invoice] = []
\ No newline at end of file
diff --git a/app/schemas/invoice.py b/app/schemas/invoice.py
index 25f30c3..49f7a4c 100644
--- a/app/schemas/invoice.py
+++ b/app/schemas/invoice.py
@@ -1,7 +1,7 @@
 from datetime import date
 from typing import List, Optional
 
-from pydantic import BaseModel, Field, validator
+from pydantic import BaseModel, Field, field_validator
 
 
 # Invoice Item schemas
@@ -25,8 +25,9 @@ class InvoiceItemInDBBase(InvoiceItemBase):
     id: int
     invoice_id: int
 
-    class Config:
-        orm_mode = True
+    model_config = {
+        "from_attributes": True
+    }
 
 
 class InvoiceItem(InvoiceItemInDBBase):
@@ -42,7 +43,7 @@ class InvoiceBase(BaseModel):
     due_date: Optional[date] = None
     notes: Optional[str] = None
     
-    @validator("status")
+    @field_validator("status")
     def status_validator(cls, v):
         allowed_statuses = ["draft", "sent", "paid"]
         if v not in allowed_statuses:
@@ -67,8 +68,9 @@ class InvoiceInDBBase(InvoiceBase):
     total_amount: float
     pdf_path: Optional[str] = None
 
-    class Config:
-        orm_mode = True
+    model_config = {
+        "from_attributes": True
+    }
 
 
 class Invoice(InvoiceInDBBase):
diff --git a/app/schemas/user.py b/app/schemas/user.py
index 3abc98b..0112a6b 100644
--- a/app/schemas/user.py
+++ b/app/schemas/user.py
@@ -1,6 +1,9 @@
 from typing import List, Optional
 
-from pydantic import BaseModel, EmailStr, Field, validator
+from pydantic import BaseModel, EmailStr, Field, field_validator
+
+# Import at module level to avoid circular imports
+from app.schemas.client import Client
 
 
 # Shared properties
@@ -17,7 +20,7 @@ class UserBase(BaseModel):
 class UserCreate(UserBase):
     password: str = Field(..., min_length=8)
     
-    @validator("password")
+    @field_validator("password")
     def password_validation(cls, v):
         if len(v) < 8:
             raise ValueError("Password must be at least 8 characters long")
@@ -30,7 +33,7 @@ class UserUpdate(UserBase):
     full_name: Optional[str] = None
     password: Optional[str] = None
 
-    @validator("password")
+    @field_validator("password")
     def password_validation(cls, v):
         if v is not None and len(v) < 8:
             raise ValueError("Password must be at least 8 characters long")
@@ -41,8 +44,9 @@ class UserUpdate(UserBase):
 class UserInDBBase(UserBase):
     id: int
 
-    class Config:
-        orm_mode = True
+    model_config = {
+        "from_attributes": True
+    }
 
 
 # Properties to return via API
@@ -57,5 +61,4 @@ class UserInDB(UserInDBBase):
 
 # User with clients
 class UserWithClients(User):
-    from app.schemas.client import Client
     clients: List[Client] = []
\ No newline at end of file