diff --git a/news/10.feature.rst b/news/10.feature.rst
new file mode 100644
index 0000000..c582d9f
--- /dev/null
+++ b/news/10.feature.rst
@@ -0,0 +1,1 @@
+Show the error details in ``ValidationError``.
diff --git a/src/plette/models/base.py b/src/plette/models/base.py
index b371db0..72cf372 100644
--- a/src/plette/models/base.py
+++ b/src/plette/models/base.py
@@ -8,6 +8,17 @@ class ValidationError(ValueError):
     def __init__(self, value, validator):
         super(ValidationError, self).__init__(value)
         self.validator = validator
+        self.value = value
+
+    def __str__(self):
+        return '{}\n{}'.format(
+            self.value,
+            '\n'.join(
+                '{}: {}'.format(k, e)
+                for k, errors in self.validator.errors.items()
+                for e in errors
+            )
+        )
 
 
 VALIDATORS = {}

Show what is failing in ValidationError
When plette emits a ValidationError, it should show more information about what is mismatching.
diff --git a/tests/test_models.py b/tests/test_models.py
index 9a172dd..a4a16bb 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -197,3 +197,17 @@ def test_del_slice(sources):
             "verify_ssl": True,
         },
     ]
+
+
+@pytest.mark.skipif(cerberus is None, reason="Skip validation without Ceberus")
+def test_validation_error():
+    data = {
+        'name': 'test',
+        'verify_ssl': 1
+    }
+    with pytest.raises(models.base.ValidationError) as exc_info:
+        models.Source.validate(data)
+
+    error_message = str(exc_info.value)
+    assert 'verify_ssl: must be of boolean type' in error_message
+    assert 'url: required field' in error_message

pip install -e .[validation]
parse_log_pytest
pytest
pytest pytest-xdist
3.6
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs @ file:///opt/conda/conda-bld/attrs_1642510447205/work
Cerberus==1.3.5
certifi==2021.5.30
execnet==1.9.0
importlib-metadata @ file:///tmp/build/80754af9/importlib-metadata_1631916693255/work
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
more-itertools @ file:///tmp/build/80754af9/more-itertools_1637733554872/work
packaging @ file:///tmp/build/80754af9/packaging_1637314298585/work
-e git+https://github.com/sarugaku/plette.git@499e99f6171c65c2a0045dbb570852d18aaa6fc0#egg=plette
pluggy @ file:///tmp/build/80754af9/pluggy_1615976315926/work
py @ file:///opt/conda/conda-bld/py_1644396412707/work
pyparsing @ file:///tmp/build/80754af9/pyparsing_1635766073266/work
pytest==6.2.4
pytest-xdist==3.0.2
six==1.17.0
toml @ file:///tmp/build/80754af9/toml_1616166611790/work
tomlkit==0.11.6
typing_extensions @ file:///opt/conda/conda-bld/typing_extensions_1647553014482/work
zipp @ file:///tmp/build/80754af9/zipp_1633618647012/work

name: plette
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - attrs=21.4.0=pyhd3eb1b0_0
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - importlib-metadata=4.8.1=py36h06a4308_0
  - importlib_metadata=4.8.1=hd3eb1b0_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - more-itertools=8.12.0=pyhd3eb1b0_0
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - packaging=21.3=pyhd3eb1b0_0
  - pip=21.2.2=py36h06a4308_0
  - pluggy=0.13.1=py36h06a4308_0
  - py=1.11.0=pyhd3eb1b0_0
  - pyparsing=3.0.4=pyhd3eb1b0_0
  - pytest=6.2.4=py36h06a4308_2
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - toml=0.10.2=pyhd3eb1b0_0
  - typing_extensions=4.1.1=pyh06a4308_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zipp=3.6.0=pyhd3eb1b0_0
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - cerberus==1.3.5
      - execnet==1.9.0
      - pytest-xdist==3.0.2
      - six==1.17.0
      - tomlkit==0.11.6
prefix: /opt/conda/envs/plette

tests/test_models.py::test_validation_error
tests/test_models.py::test_hash_from_hash tests/test_models.py::test_hash_from_line tests/test_models.py::test_hash_as_line tests/test_models.py::test_source_from_data tests/test_models.py::test_source_as_data_expanded tests/test_models.py::test_source_as_data_expanded_partial tests/test_models.py::test_requires_python_version tests/test_models.py::test_requires_python_version_no_full_version tests/test_models.py::test_requires_python_full_version tests/test_models.py::test_requires_python_full_version_no_version tests/test_models.py::test_requires_no_duplicate_python_version tests/test_models.py::test_package_str tests/test_models.py::test_package_dict tests/test_models.py::test_package_wrong_key tests/test_models.py::test_meta tests/test_models.py::test_get_slice tests/test_models.py::test_set_slice tests/test_models.py::test_del_slice
news/10.feature.rst src/plette/models/base.py
news/10.feature.rst src/plette/models/base.py