diff --git a/gns3server/api/routes/controller/dependencies/authentication.py b/gns3server/api/routes/controller/dependencies/authentication.py
index 1043db717..1517e0572 100644
--- a/gns3server/api/routes/controller/dependencies/authentication.py
+++ b/gns3server/api/routes/controller/dependencies/authentication.py
@@ -55,7 +55,7 @@ async def get_user_from_token(
     user_repo: UsersRepository = Depends(get_repository(UsersRepository)),
     api_keys_repo: ApiKeysRepository = Depends(get_repository(ApiKeysRepository)),
     token: Optional[str] = Query(None, include_in_schema=False),
-) -> schemas.User:
+) -> models.User:
 
     if bearer_token:
         # bearer token is used first, then any token passed as a URL parameter
@@ -169,7 +169,7 @@ async def get_current_active_user_from_websocket(
     websocket: WebSocket,
     token: str = Query(...),
     user_repo: UsersRepository = Depends(get_repository(UsersRepository)),
-) -> Optional[schemas.User]:
+) -> Optional[models.User]:
 
     # Extract requested subprotocols from headers for proper WebSocket negotiation
     # This is critical for protocols like xpra that require specific subprotocols
@@ -238,4 +238,5 @@ async def get_current_active_user_from_websocket(
         websocket_error = {"action": "log.error", "event": {"message": err_msg}}
         await websocket.send_json(websocket_error)
         log.error(err_msg)
-        return await websocket.close(code=1008)
+        await websocket.close(code=1008)
+        return None
diff --git a/gns3server/db/models/api_keys.py b/gns3server/db/models/api_keys.py
index 5cc40eb0b..ec320f9dd 100644
--- a/gns3server/db/models/api_keys.py
+++ b/gns3server/db/models/api_keys.py
@@ -14,7 +14,10 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import uuid
+
 from sqlalchemy import Column, String, Boolean, DateTime, ForeignKey, func
+from sqlalchemy.orm import Mapped, mapped_column
 
 from .base import BaseTable, GUID
 
@@ -22,8 +25,10 @@ from .base import BaseTable, GUID
 class ApiKey(BaseTable):
     __tablename__ = "api_keys"
 
-    api_key_id = Column(GUID, primary_key=True)
-    user_id = Column(GUID, ForeignKey("users.user_id", ondelete="CASCADE"), nullable=False, index=True)
+    api_key_id: Mapped[uuid.UUID] = mapped_column(GUID, primary_key=True)
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        GUID, ForeignKey("users.user_id", ondelete="CASCADE"), nullable=False, index=True
+    )
     name = Column(String(128), nullable=False)
     key_hash = Column(String(128), nullable=False)
     key_prefix = Column(String(8), nullable=False)
diff --git a/gns3server/db/models/templates.py b/gns3server/db/models/templates.py
index 62ea74a9e..0450be881 100644
--- a/gns3server/db/models/templates.py
+++ b/gns3server/db/models/templates.py
@@ -16,19 +16,26 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+import uuid
+from typing import Optional
+
 from sqlalchemy import Boolean, Column, String, Integer, Float, ForeignKey, JSON
-from sqlalchemy.orm import relationship
+from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from .base import BaseTable, generate_uuid, GUID
 from .images import image_template_map
 
 
+def template_id_column() -> Mapped[uuid.UUID]:
+    return mapped_column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+
+
 class Template(BaseTable):
     __tablename__ = "templates"
 
-    template_id = Column(GUID, primary_key=True, default=generate_uuid)
+    template_id: Mapped[uuid.UUID] = mapped_column(GUID, primary_key=True, default=generate_uuid)
     name = Column(String, index=True)
-    version = Column(String)
+    version: Mapped[Optional[str]] = mapped_column(String)
     category = Column(String)
     default_name_format = Column(String)
     symbol = Column(String)
@@ -36,7 +43,7 @@ class Template(BaseTable):
     usage = Column(String)
     netmiko_device_type = Column(String)
     appliance_metadata = Column(JSON)
-    template_type = Column(String)
+    template_type: Mapped[str] = mapped_column(String, nullable=True)
     tags = Column(JSON)
     compute_id = Column(String)
     images = relationship("Image", secondary=image_template_map, back_populates="templates")
@@ -50,7 +57,7 @@ class Template(BaseTable):
 class CloudTemplate(Template):
     __tablename__ = "cloud_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     ports_mapping = Column(JSON)
     remote_console_host = Column(String)
     remote_console_port = Column(Integer)
@@ -63,7 +70,7 @@ class CloudTemplate(Template):
 class DockerTemplate(Template):
     __tablename__ = "docker_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     image = Column(String)
     adapters = Column(Integer)
     mac_address = Column(String)
@@ -88,10 +95,10 @@ class DockerTemplate(Template):
 class DynamipsTemplate(Template):
     __tablename__ = "dynamips_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
-    platform = Column(String)
+    template_id: Mapped[uuid.UUID] = template_id_column()
+    platform: Mapped[str] = mapped_column(String, nullable=True)
     chassis = Column(String)
-    image = Column(String)
+    image: Mapped[str] = mapped_column(String, nullable=True)
     exec_area = Column(Integer)
     mmap = Column(Boolean)
     mac_addr = Column(String)
@@ -130,7 +137,7 @@ class DynamipsTemplate(Template):
 class EthernetHubTemplate(Template):
     __tablename__ = "ethernet_hub_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     ports_mapping = Column(JSON)
 
     __mapper_args__ = {"polymorphic_identity": "ethernet_hub", "polymorphic_load": "selectin"}
@@ -139,7 +146,7 @@ class EthernetHubTemplate(Template):
 class EthernetSwitchTemplate(Template):
     __tablename__ = "ethernet_switch_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     ports_mapping = Column(JSON)
     console_type = Column(String)
 
@@ -149,8 +156,8 @@ class EthernetSwitchTemplate(Template):
 class IOUTemplate(Template):
     __tablename__ = "iou_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
-    path = Column(String)
+    template_id: Mapped[uuid.UUID] = template_id_column()
+    path: Mapped[str] = mapped_column(String, nullable=True)
     ethernet_adapters = Column(Integer)
     serial_adapters = Column(Integer)
     ram = Column(Integer)
@@ -168,7 +175,7 @@ class IOUTemplate(Template):
 class QemuTemplate(Template):
     __tablename__ = "qemu_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     qemu_path = Column(String)
     platform = Column(String)
     linked_clone = Column(Boolean)
@@ -214,7 +221,7 @@ class QemuTemplate(Template):
 class VirtualBoxTemplate(Template):
     __tablename__ = "virtualbox_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     vmname = Column(String)
     ram = Column(Integer)
     linked_clone = Column(Boolean)
@@ -236,7 +243,7 @@ class VirtualBoxTemplate(Template):
 class VMwareTemplate(Template):
     __tablename__ = "vmware_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     vmx_path = Column(String)
     linked_clone = Column(Boolean)
     first_port_name = Column(String)
@@ -257,7 +264,7 @@ class VMwareTemplate(Template):
 class VPCSTemplate(Template):
     __tablename__ = "vpcs_templates"
 
-    template_id = Column(GUID, ForeignKey("templates.template_id", ondelete="CASCADE"), primary_key=True)
+    template_id: Mapped[uuid.UUID] = template_id_column()
     base_script_file = Column(String)
     console_type = Column(String)
     console_auto_start = Column(Boolean, default=False)
diff --git a/gns3server/db/repositories/templates.py b/gns3server/db/repositories/templates.py
index 582404301..9d5c1a9af 100644
--- a/gns3server/db/repositories/templates.py
+++ b/gns3server/db/repositories/templates.py
@@ -16,11 +16,13 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import uuid
 import logging
 
 from uuid import UUID
-from typing import List, Union, Optional
+from typing import List, Union, Optional, cast
 from sqlalchemy import select, delete
+from sqlalchemy.engine import CursorResult
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import selectinload
 from sqlalchemy.orm.session import make_transient
@@ -64,7 +66,7 @@ class TemplatesRepository(BaseRepository):
         result = await self._db_session.execute(query)
         return result.scalars().first()
 
-    async def get_template_by_name_and_version(self, name: str, version: str) -> Union[None, models.Template]:
+    async def get_template_by_name_and_version(self, name: str, version: Optional[str]) -> Union[None, models.Template]:
 
         query = (
             select(models.Template)
@@ -89,7 +91,7 @@ class TemplatesRepository(BaseRepository):
 
         query = select(models.Template).options(selectinload(models.Template.images))
         result = await self._db_session.execute(query)
-        return result.scalars().all()
+        return list(result.scalars().all())
 
     async def create_template(self, template_type: str, template_settings: dict) -> models.Template:
 
@@ -100,7 +102,7 @@ class TemplatesRepository(BaseRepository):
         await self._db_session.refresh(db_template)
         return db_template
 
-    async def update_template(self, db_template: models.Template, template_settings: dict) -> schemas.Template:
+    async def update_template(self, db_template: models.Template, template_settings: dict) -> models.Template:
 
         # update the fields directly because update() query couldn't work
         for key, value in template_settings.items():
@@ -114,9 +116,9 @@ class TemplatesRepository(BaseRepository):
         query = delete(models.Template).where(models.Template.template_id == template_id)
         result = await self._db_session.execute(query)
         await self._db_session.commit()
-        return result.rowcount > 0
+        return cast(CursorResult, result).rowcount > 0
 
-    async def duplicate_template(self, template_id: UUID) -> Optional[schemas.Template]:
+    async def duplicate_template(self, template_id: UUID) -> Optional[models.Template]:
 
         query = (
             select(models.Template)
@@ -128,7 +130,7 @@ class TemplatesRepository(BaseRepository):
             # duplicate db object with new primary key (template_id)
             self._db_session.expunge(db_template)
             make_transient(db_template)
-            db_template.template_id = None
+            db_template.template_id = uuid.uuid4()
             self._db_session.add(db_template)
             await self._db_session.commit()
             await self._db_session.refresh(db_template)
@@ -205,4 +207,4 @@ class TemplatesRepository(BaseRepository):
 
         query = select(models.Image).join(models.Image.templates).filter(models.Template.template_id == template_id)
         result = await self._db_session.execute(query)
-        return result.scalars().all()
+        return list(result.scalars().all())
diff --git a/gns3server/schemas/controller/tokens.py b/gns3server/schemas/controller/tokens.py
index 29197acfa..2ac14dda6 100644
--- a/gns3server/schemas/controller/tokens.py
+++ b/gns3server/schemas/controller/tokens.py
@@ -25,7 +25,7 @@ class Token(BaseModel):
 
 
 class TokenData(BaseModel):
-    username: Optional[str] = None
+    username: str
     token_version: int = 0
     token_use: str = "access"
 
diff --git a/gns3server/services/templates.py b/gns3server/services/templates.py
index 10a167c89..00f02b4b0 100644
--- a/gns3server/services/templates.py
+++ b/gns3server/services/templates.py
@@ -20,7 +20,7 @@ import pydantic
 
 from uuid import UUID
 from fastapi.encoders import jsonable_encoder
-from typing import List
+from typing import List, Optional
 
 from gns3server import schemas
 from gns3server.config import Config
@@ -34,7 +34,7 @@ from gns3server.controller.controller_error import (
 )
 
 
-TEMPLATE_TYPE_TO_SCHEMA = {
+TEMPLATE_TYPE_TO_SCHEMA: dict[str, type[pydantic.BaseModel]] = {
     "cloud": schemas.CloudTemplate,
     "ethernet_hub": schemas.EthernetHubTemplate,
     "ethernet_switch": schemas.EthernetSwitchTemplate,
@@ -47,7 +47,7 @@ TEMPLATE_TYPE_TO_SCHEMA = {
     "qemu": schemas.QemuTemplate,
 }
 
-TEMPLATE_TYPE_TO_UPDATE_SCHEMA = {
+TEMPLATE_TYPE_TO_UPDATE_SCHEMA: dict[str, type[pydantic.BaseModel]] = {
     "cloud": schemas.CloudTemplateUpdate,
     "ethernet_hub": schemas.EthernetHubTemplateUpdate,
     "ethernet_switch": schemas.EthernetSwitchTemplateUpdate,
@@ -59,7 +59,7 @@ TEMPLATE_TYPE_TO_UPDATE_SCHEMA = {
     "qemu": schemas.QemuTemplateUpdate,
 }
 
-DYNAMIPS_PLATFORM_TO_SCHEMA = {
+DYNAMIPS_PLATFORM_TO_SCHEMA: dict[str, type[pydantic.BaseModel]] = {
     "c7200": schemas.C7200DynamipsTemplate,
     "c3745": schemas.C3745DynamipsTemplate,
     "c3725": schemas.C3725DynamipsTemplate,
@@ -69,7 +69,7 @@ DYNAMIPS_PLATFORM_TO_SCHEMA = {
     "c1700": schemas.C1700DynamipsTemplate,
 }
 
-DYNAMIPS_PLATFORM_TO_UPDATE_SCHEMA = {
+DYNAMIPS_PLATFORM_TO_UPDATE_SCHEMA: dict[str, type[pydantic.BaseModel]] = {
     "c7200": schemas.C7200DynamipsTemplateUpdate,
     "c3745": schemas.C3745DynamipsTemplateUpdate,
     "c3725": schemas.C3725DynamipsTemplateUpdate,
@@ -169,11 +169,12 @@ class TemplatesService:
         for builtin_template in BUILTIN_TEMPLATES:
             builtin_template["symbol"] = self._controller.symbols.resolve_symbol(builtin_template["symbol"])
 
-    def get_builtin_template(self, template_id: UUID) -> dict:
+    def get_builtin_template(self, template_id: UUID) -> Optional[dict]:
 
         for builtin_template in BUILTIN_TEMPLATES:
             if builtin_template["template_id"] == template_id:
                 return jsonable_encoder(builtin_template)
+        return None
 
     def _base_path(self):
         return self._templates_repo.configs_path()
@@ -303,7 +304,7 @@ class TemplatesService:
         try:
             # validate the update settings
             update_settings = jsonable_encoder(template_update, exclude_unset=True)
-            if db_template.template_type == "dynamips":
+            if isinstance(db_template, models.DynamipsTemplate):
                 template_schema = DYNAMIPS_PLATFORM_TO_UPDATE_SCHEMA[db_template.platform]
             else:
                 template_schema = TEMPLATE_TYPE_TO_UPDATE_SCHEMA[db_template.template_type]
@@ -312,9 +313,9 @@ class TemplatesService:
             raise ControllerBadRequestError(f"JSON schema error received while updating template: {e}")
 
         images_to_add_to_template = await self._find_images(db_template.template_type, template_settings)
-        if db_template.template_type == "dynamips" and "image" in template_settings:
+        if isinstance(db_template, models.DynamipsTemplate) and "image" in template_settings:
             await self._remove_image(db_template.template_id, db_template.image)
-        elif db_template.template_type == "iou" and "path" in template_settings:
+        elif isinstance(db_template, models.IOUTemplate) and "path" in template_settings:
             await self._remove_image(db_template.template_id, db_template.path)
         elif db_template.template_type == "qemu":
             for key in template_update.model_dump().keys():