diff --git a/apis/paios/openapi.yaml b/apis/paios/openapi.yaml
index cd0cb59..0f365cd 100644
--- a/apis/paios/openapi.yaml
+++ b/apis/paios/openapi.yaml
@@ -1185,10 +1185,12 @@ components:
         resource_id:
           $ref: '#/components/schemas/uuid4'
         user_id:
-          $ref: '#/components/schemas/uuid4'
+          type: string
+          nullable: true
         expiration_dt:
           type: string
           format: date-time
+          nullable: true
         is_revoked:
           type: boolean
       required:
diff --git a/backend/api/SharesView.py b/backend/api/SharesView.py
index 7f08e0d..b04f523 100644
--- a/backend/api/SharesView.py
+++ b/backend/api/SharesView.py
@@ -15,22 +15,28 @@ async def get(self, id: str):
         return JSONResponse(share.model_dump(), status_code=200)
 
     async def post(self, body: dict):
-        print("expiration_dt: {}".format(body['expiration_dt']))
-        expiration_dt = datetime.fromisoformat(body['expiration_dt']).astimezone(tz=timezone.utc)
-        print("converted expiration_dt: {}".format(expiration_dt))
+        expiration_dt = None
+        if 'expiration_dt' in body and body['expiration_dt'] is not None:
+            expiration_dt = datetime.fromisoformat(body['expiration_dt']).astimezone(tz=timezone.utc)
+        user_id = None
+        if 'user_id' in body and body['user_id']:
+            user_id = body['user_id']
         new_share = await self.slm.create_share(resource_id=body['resource_id'],
-                                                user_id=body['user_id'],
+                                                user_id=user_id,
                                                 expiration_dt=expiration_dt,
                                                 is_revoked=False)
         return JSONResponse(new_share.model_dump(), status_code=201, headers={'Location': f'{api_base_url}/shares/{new_share.id}'})
 
     async def put(self, id: str, body: dict):
-        print("expiration_dt: {}".format(body['expiration_dt']))
-        expiration_dt = datetime.fromisoformat(body['expiration_dt']).astimezone(tz=timezone.utc)
-        print("converted expiration_dt: {}".format(expiration_dt))
+        expiration_dt = None
+        if 'expiration_dt' in body and body['expiration_dt'] is not None:
+            expiration_dt = datetime.fromisoformat(body['expiration_dt']).astimezone(tz=timezone.utc)
+        user_id = None
+        if 'user_id' in body and body['user_id']:
+            user_id = body['user_id']
         updated_share = await self.slm.update_share(id,
                                                     resource_id=body['resource_id'],
-                                                    user_id=body['user_id'],
+                                                    user_id=user_id,
                                                     expiration_dt=expiration_dt,
                                                     is_revoked=body['is_revoked'])
         if updated_share is None:
diff --git a/backend/managers/SharesManager.py b/backend/managers/SharesManager.py
index 01c6e15..f5bbb92 100644
--- a/backend/managers/SharesManager.py
+++ b/backend/managers/SharesManager.py
@@ -81,8 +81,6 @@ async def retrieve_shares(self, offset: int = 0, limit: int = 100, sort_by: Opti
         async with db_session_context() as session:
             query = select(Share)
 
-            print("filters: {}".format(filters))
-
             if filters:
                 for key, value in filters.items():
                     if isinstance(value, list):
diff --git a/backend/schemas.py b/backend/schemas.py
index 83e1d6e..4007dfe 100644
--- a/backend/schemas.py
+++ b/backend/schemas.py
@@ -70,9 +70,17 @@ class ShareBaseSchema(BaseModel):
     expiration_dt: Optional[datetime] = None
     is_revoked: Optional[bool] = False
 
-    @field_serializer('expiration_dt')
-    def serialize_dt(self, dt: datetime, _info):
-        return dt.strftime('%Y-%m-%dT%H:%M:%SZ')
+    @field_serializer('user_id')
+    def serialize_user_id(self, user_id: str, _info):
+        if user_id:
+            return user_id
+        else:
+            return ""
+
+    @field_serializer('expiration_dt', when_used='unless-none')
+    def serialize_expiration_dt(self, dt: datetime, _info):
+        if dt:
+            return dt.strftime('%Y-%m-%dT%H:%M:%SZ')
 
 
 class ShareCreateSchema(ShareBaseSchema):