diff --git a/pyproject.toml b/pyproject.toml
index 02ac0ca3..839510f2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,7 +35,7 @@ dependencies = [
     "qastle>=0.17",
     "func_adl>=3.2.6",
     "requests>=2.31",
-    "pydantic>=1.10,<2.0",  # FIXME: Adopt pydantic 2.0 API
+    "pydantic>=2.0",
     "httpx>=0.24",
     "miniopy-async>=1.15",
     "tinydb>=4.7",
diff --git a/servicex/__init__.py b/servicex/__init__.py
index 005a2e04..5a30dc27 100644
--- a/servicex/__init__.py
+++ b/servicex/__init__.py
@@ -29,7 +29,7 @@
 from servicex import models
 from servicex import servicex_client
 from servicex import dataset_identifier
-from servicex.databinder_models import Sample, General, Definition, ServiceXSpec
+from servicex.databinder_models import Sample, General, DefinitionDict, ServiceXSpec
 from servicex.func_adl.func_adl_dataset import FuncADLQuery
 from servicex.servicex_client import ServiceXClient, deliver
 from .query import Query
@@ -53,7 +53,7 @@
     "FuncADLQuery",
     "Sample",
     "General",
-    "Definition",
+    "DefinitionDict",
     "ServiceXSpec",
     "deliver"
 ]
diff --git a/servicex/configuration.py b/servicex/configuration.py
index 1f75aa33..50b7b858 100644
--- a/servicex/configuration.py
+++ b/servicex/configuration.py
@@ -30,7 +30,7 @@
 from pathlib import Path, PurePath
 from typing import List, Optional, Dict
 
-from pydantic import BaseModel, Field, validator
+from pydantic import BaseModel, Field, AliasChoices, model_validator
 
 import yaml
 
@@ -38,17 +38,20 @@
 class Endpoint(BaseModel):
     endpoint: str
     name: str
-    token: Optional[str]
+    token: Optional[str] = ""
 
 
 class Configuration(BaseModel):
     api_endpoints: List[Endpoint]
     default_endpoint: Optional[str] = Field(alias="default-endpoint", default=None)
-    cache_path: Optional[str] = Field(alias="cache-path", default=None)
+    cache_path: Optional[str] = Field(
+        validation_alias=AliasChoices("cache-path", "cache_path"), default=None
+    )
+
     shortened_downloaded_filename: Optional[bool] = False
 
-    @validator("cache_path", always=True)
-    def expand_cache_path(cls, v):
+    @model_validator(mode="after")
+    def expand_cache_path(self):
         """
         Expand the cache path to a full path, and create it if it doesn't exist.
         Expand ${USER} to be the user name on the system. Works for windows, too.
@@ -56,10 +59,10 @@ def expand_cache_path(cls, v):
         :return:
         """
         # create a folder inside the tmp directory if not specified in cache_path
-        if not v:
-            v = "/tmp/servicex_${USER}"
+        if not self.cache_path:
+            self.cache_path = "/tmp/servicex_${USER}"
 
-        s_path = os.path.expanduser(v)
+        s_path = os.path.expanduser(self.cache_path)
 
         # If they have tried to use the USER or UserName as an expansion, and it has failed, then
         # translate it to maintain harmony across platforms.
@@ -75,10 +78,11 @@ def expand_cache_path(cls, v):
             p = Path(p_p)
         p.mkdir(exist_ok=True, parents=True)
 
-        return p.as_posix()
+        self.cache_path = p.as_posix()
+        return self
 
     class Config:
-        allow_population_by_field_name = True
+        populate_by_name = True
 
     def endpoint_dict(self) -> Dict[str, Endpoint]:
         return {endpoint.name: endpoint for endpoint in self.api_endpoints}
@@ -98,7 +102,7 @@ def read(cls, config_path: Optional[str] = None):
             yaml_config = cls._add_from_path(walk_up_tree=True)
 
         if yaml_config:
-            return Configuration(**yaml_config)
+            return Configuration.model_validate(yaml_config)
         else:
             path_extra = f"in {config_path}" if config_path else ""
             raise NameError(
diff --git a/servicex/databinder_models.py b/servicex/databinder_models.py
index 691eca1a..e2ebea1e 100644
--- a/servicex/databinder_models.py
+++ b/servicex/databinder_models.py
@@ -27,7 +27,11 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 from enum import Enum
 from typing import Union, Optional, Callable, List
-from pydantic import BaseModel, Field, root_validator, constr, validator
+from pydantic import (
+    BaseModel,
+    Field,
+    model_validator,
+)
 
 from servicex.dataset_identifier import RucioDatasetIdentifier, FileListDataset
 from servicex.func_adl import func_adl_dataset
@@ -35,9 +39,9 @@
 
 class Sample(BaseModel):
     Name: str
-    Codegen: Optional[str]
-    RucioDID: Optional[str]
-    XRootDFiles: Optional[Union[str, List[str]]]
+    Codegen: Optional[str] = None
+    RucioDID: Optional[str] = None
+    XRootDFiles: Optional[Union[str, List[str]]] = None
     NFiles: Optional[int] = Field(default=None)
     Function: Optional[Union[str, Callable]] = Field(default=None)
     Query: Optional[Union[str, func_adl_dataset.Query]] = Field(default=None)
@@ -54,29 +58,31 @@ def dataset_identifier(self):
         elif self.XRootDFiles:
             return FileListDataset(self.XRootDFiles)
 
-    @root_validator
+    @model_validator(mode="before")
+    @classmethod
     def validate_did_xor_file(cls, values):
         """
         Ensure that only one of RootFile or RucioDID is specified.
         :param values:
         :return:
         """
-        if values['XRootDFiles'] and values['RucioDID']:
+        if "XRootDFiles" in values and "RucioDID" in values:
             raise ValueError("Only specify one of XRootDFiles or RucioDID, not both.")
-        if not values['XRootDFiles'] and not values['RucioDID']:
+        if "XRootDFiles" not in values and "RucioDID" not in values:
             raise ValueError("Must specify one of XRootDFiles or RucioDID.")
         return values
 
-    @root_validator
+    @model_validator(mode="before")
+    @classmethod
     def validate_function_xor_query(cls, values):
         """
         Ensure that only one of Function or Query is specified.
         :param values:
         :return:
         """
-        if values['Function'] and values['Query']:
+        if "Function" in values and "Query" in values:
             raise ValueError("Only specify one of Function or Query, not both.")
-        if not values['Function'] and not values['Query']:
+        if "Function" not in values and "Query" not in values:
             raise ValueError("Must specify one of Function or Query.")
         return values
 
@@ -92,17 +98,21 @@ class DeliveryEnum(str, Enum):
 
     ServiceX: str = Field(..., alias="ServiceX")
     Codegen: str
-    OutputFormat: Union[OutputFormatEnum,
-        constr(regex='^(parquet|root-file)$')] = Field(default=OutputFormatEnum.root)  # NOQA F722
+    OutputFormat: OutputFormatEnum = (
+        Field(default=OutputFormatEnum.root, pattern="^(parquet|root-file)$")
+    )  # NOQA F722
 
-    Delivery: Union[DeliveryEnum, constr(regex='^(LocalCache|SignedURLs)$')] = Field(default=DeliveryEnum.LocalCache) # NOQA F722
+    Delivery: DeliveryEnum = Field(
+        default=DeliveryEnum.LocalCache, pattern="^(LocalCache|SignedURLs)$"
+    )  # NOQA F722
 
 
-class Definition(BaseModel):
+class DefinitionDict(BaseModel):
     class Config:
         extra = "allow"  # Allow additional fields not defined in the model
 
-    @root_validator
+    @model_validator(mode="before")
+    @classmethod
     def check_def_name(cls, values):
         """
         Ensure that the definition name is DEF_XXX format
@@ -111,31 +121,36 @@ def check_def_name(cls, values):
         """
         for field in values:
             if not field.startswith("DEF_"):
-                raise ValueError(f"Definition key {field} does not meet the convention of DEF_XXX format") # NOQA E501
+                raise ValueError(
+                    f"Definition key {field} does not meet the convention of DEF_XXX format"
+                )  # NOQA E501
         return values
 
 
 class ServiceXSpec(BaseModel):
     General: General
     Sample: List[Sample]
-    Definition: Optional[Definition]
-
-    @validator('Sample')
-    def check_tree_property(cls, v, values):
-        if 'General' in values and values['General'].Codegen != 'uproot':
-            for sample in v:
-                if 'Tree' in sample:
-                    raise ValueError('"Tree" property is not allowed when codegen is not "uproot"')
-        return v
-
-    @root_validator(pre=False, skip_on_failure=True)
-    def replace_definition(cls, values):
+    Definition: Optional[DefinitionDict] = None
+
+    @model_validator(mode="after")
+    def check_tree_property(self):
+        if self.General and self.General.Codegen != "uproot":
+            for sample in self.Sample:
+                if "Tree" in sample:
+                    raise ValueError(
+                        '"Tree" property is not allowed when codegen is not "uproot"'
+                    )
+        return self
+
+    @model_validator(mode="after")
+    def replace_definition(self):
         """
         Replace the definition name with the actual definition value looking
         through the Samples and the General sections
         :param values:
         :return:
         """
+
         def replace_value_from_def(value, defs):
             """
             Replace the value with the actual definition value
@@ -154,14 +169,14 @@ def replace_value_from_def(value, defs):
                         raise ValueError(f"Definition {value} not found")
             return value
 
-        if 'Definition' in values and values['Definition'] is not None:
-            defs = values['Definition'].dict()
+        if self.Definition and self.Definition:
+            defs = self.Definition.dict()
         else:
             defs = {}
 
-        for sample_field in values['Sample']:
+        for sample_field in self.Sample:
             replace_value_from_def(sample_field.__dict__, defs)
 
-        replace_value_from_def(values['General'].__dict__, defs)
+        replace_value_from_def(self.General.__dict__, defs)
 
-        return values
+        return self
diff --git a/servicex/models.py b/servicex/models.py
index 40978720..88f8fc06 100644
--- a/servicex/models.py
+++ b/servicex/models.py
@@ -29,7 +29,7 @@
 from datetime import datetime
 from enum import Enum
 
-from pydantic import BaseModel, Field, validator
+from pydantic import BaseModel, Field, field_validator
 from typing import List, Optional
 
 
@@ -37,6 +37,7 @@ class ResultDestination(str, Enum):
     r"""
     Direct the output to object store or posix volume
     """
+
     object_store = "object-store"
     volume = "volume"
 
@@ -45,6 +46,7 @@ class ResultFormat(str, Enum):
     r"""
     Specify the file format for the generated output
     """
+
     parquet = "parquet"
     root = "root-file"
 
@@ -53,6 +55,7 @@ class Status(str, Enum):
     r"""
     Status of a submitted transform
     """
+
     complete = ("Complete",)
     fatal = ("Fatal",)
     canceled = ("Canceled",)
@@ -65,6 +68,7 @@ class TransformRequest(BaseModel):
     r"""
     Transform request sent to ServiceX
     """
+
     title: Optional[str] = None
     did: Optional[str] = None
     file_list: Optional[List[str]] = Field(default=None, alias="file-list")
@@ -72,11 +76,13 @@ class TransformRequest(BaseModel):
     image: Optional[str] = None
     codegen: str
     tree_name: Optional[str] = Field(default=None, alias="tree-name")
-    result_destination: ResultDestination = Field(alias="result-destination")
-    result_format: ResultFormat = Field(alias="result-format")
+    result_destination: ResultDestination = Field(
+        serialization_alias="result-destination"
+    )
+    result_format: ResultFormat = Field(serialization_alias="result-format")
 
     class Config:
-        allow_population_by_field_name = True
+        populate_by_name = True
 
     def compute_hash(self):
         r"""
@@ -105,30 +111,32 @@ class TransformStatus(BaseModel):
     r"""
     Status object returned by servicex
     """
+
     request_id: str
     did: str
-    title: Optional[str]
+    title: Optional[str] = None
     selection: str
-    tree_name: Optional[str] = Field(alias="tree-name")
+    tree_name: Optional[str] = Field(validation_alias="tree-name")
     image: str
-    result_destination: ResultDestination = Field(alias="result-destination")
-    result_format: ResultFormat = Field(alias="result-format")
-    generated_code_cm: str = Field(alias="generated-code-cm")
+    result_destination: ResultDestination = Field(validation_alias="result-destination")
+    result_format: ResultFormat = Field(validation_alias="result-format")
+    generated_code_cm: str = Field(validation_alias="generated-code-cm")
     status: Status
-    app_version: str = Field(alias="app-version")
+    app_version: str = Field(validation_alias="app-version")
     files: int
-    files_completed: int = Field(alias="files-completed")
-    files_failed: int = Field(alias="files-failed")
-    files_remaining: Optional[int] = Field(alias="files-remaining")
-    submit_time: datetime = Field(alias="submit-time")
-    finish_time: Optional[datetime] = Field(alias="finish-time")
-    minio_endpoint: Optional[str] = Field(alias="minio-endpoint")
-    minio_secured: Optional[bool] = Field(alias="minio-secured")
-    minio_access_key: Optional[str] = Field(alias="minio-access-key")
-    minio_secret_key: Optional[str] = Field(alias="minio-secret-key")
-    log_url: Optional[str] = Field(alias="log-url")
-
-    @validator("finish_time", pre=True)
+    files_completed: int = Field(validation_alias="files-completed")
+    files_failed: int = Field(validation_alias="files-failed")
+    files_remaining: Optional[int] = Field(validation_alias="files-remaining", default=0)
+    submit_time: datetime = Field(validation_alias="submit-time", default=None)
+    finish_time: Optional[datetime] = Field(validation_alias="finish-time", default=None)
+    minio_endpoint: Optional[str] = Field(validation_alias="minio-endpoint", default=None)
+    minio_secured: Optional[bool] = Field(validation_alias="minio-secured", default=None)
+    minio_access_key: Optional[str] = Field(validation_alias="minio-access-key", default=None)
+    minio_secret_key: Optional[str] = Field(validation_alias="minio-secret-key", default=None)
+    log_url: Optional[str] = Field(validation_alias="log-url", default=None)
+
+    @field_validator("finish_time", mode="before")
+    @classmethod
     def parse_finish_time(cls, v):
         if isinstance(v, str) and v == "None":
             return None
@@ -139,6 +147,7 @@ class ResultFile(BaseModel):
     r"""
     Record reporting the properties of a transformed file result
     """
+
     filename: str
     size: int
     extension: str
@@ -149,6 +158,7 @@ class TransformedResults(BaseModel):
     Returned for a submission. Gives you everything you need to know about a completed
     transform.
     """
+
     hash: str
     title: str
     codegen: str
@@ -159,4 +169,4 @@ class TransformedResults(BaseModel):
     signed_url_list: List[str]
     files: int
     result_format: ResultFormat
-    log_url: Optional[str]
+    log_url: Optional[str] = None
diff --git a/tests/conftest.py b/tests/conftest.py
index 5884709b..56b7c1ce 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -149,7 +149,7 @@ def completed_status() -> TransformStatus:
             "files-failed": 0,
             "files-remaining": 1,
             "submit-time": "2023-05-25T20:05:05.564137Z",
-            "finish-time": "None",
+            "finish-time": None,
             "minio-endpoint": "minio.org:9000",
             "minio-secured": False,
             "minio-access-key": "miniouser",
diff --git a/tests/temp_dir2/out_dict.yml b/tests/temp_dir2/out_dict.yml
new file mode 100644
index 00000000..bfa6240b
--- /dev/null
+++ b/tests/temp_dir2/out_dict.yml
@@ -0,0 +1,5 @@
+general_info: {}
+samples:
+  sampleA:
+  - a
+  - b
diff --git a/tests/test_databinder.py b/tests/test_databinder.py
index d8154662..58ce0cd3 100644
--- a/tests/test_databinder.py
+++ b/tests/test_databinder.py
@@ -34,13 +34,13 @@ def test_load_config():
         ],
         "Definition": {"DEF_a": "a"},
     }
-    new_config = ServiceXSpec.parse_obj(config)
+    new_config = ServiceXSpec.model_validate(config)
     assert new_config.Sample[0].Function == "a"
 
 
 def test_single_root_file():
 
-    spec = ServiceXSpec.parse_obj(
+    spec = ServiceXSpec.model_validate(
         basic_spec(
             samples=[
                 {
diff --git a/tests/test_servicex_dataset.py b/tests/test_servicex_dataset.py
index 77464a25..1f902f82 100644
--- a/tests/test_servicex_dataset.py
+++ b/tests/test_servicex_dataset.py
@@ -60,7 +60,7 @@
         "files-failed": 0,
         "files-remaining": None,
         "submit-time": "2023-05-25T20:05:05.564137Z",
-        "finish-time": "None",
+        "finish-time": None,
         "minio-endpoint": "minio.org:9000",
         "minio-secured": False,
         "minio-access-key": "miniouser",