diff --git a/CHANGELOG.md b/CHANGELOG.md
index 264c92e..e2cf62a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- `data_validation_error` (HTTP 422) now raises `ContentValidationFailed` instead of a bare `FoxnoseAPIError`. This is the code a Flux resource write returns for a schema violation, so the most common way to hit one was not caught by `except ContentValidationFailed`, and callers had to match on `status_code == 422` instead. The `errors` list and `errors_truncated` flag are populated from the same detail payload as `content_validation_failed`, and `error_code` still reports what the server sent.
+
 ## [0.6.0] - 2026-07-16
 
 ### Added
diff --git a/src/foxnose_sdk/errors.py b/src/foxnose_sdk/errors.py
index 6935089..601a4d0 100644
--- a/src/foxnose_sdk/errors.py
+++ b/src/foxnose_sdk/errors.py
@@ -101,8 +101,13 @@ class ExternalIdConflict(FoxnoseAPIError):
 
 
 class ContentValidationFailed(FoxnoseAPIError):
-    """Raised on HTTP 422 ``content_validation_failed`` — the submitted ``data``
-    failed the collection's schema.
+    """Raised on HTTP 422 when submitted ``data`` fails the collection's schema.
+
+    Two server error codes mean this, and both map here: ``content_validation_
+    failed`` and ``data_validation_error``. The latter is what a Flux resource
+    write returns, so leaving it unmapped meant the most common way to hit a
+    schema violation raised a bare ``FoxnoseAPIError``, and
+    ``except ContentValidationFailed`` never fired for it.
 
     ``errors`` is the list of individual validation problems, each a mapping that
     includes a ``json_path`` locating the offending field. ``errors_truncated`` is
@@ -137,6 +142,15 @@ class FoxnoseTransportError(FoxnoseError):
     """Raised when the HTTP layer fails before receiving a response."""
 
 
+# Both codes describe the same failure -- submitted data rejected by the
+# collection schema -- and carry the same detail shape. The resource-write path
+# raises RevisionValidationError ("data_validation_error"); other paths raise
+# the content variant.
+_CONTENT_VALIDATION_CODES = frozenset(
+    {"content_validation_failed", "data_validation_error"}
+)
+
+
 def _validation_errors_from_detail(detail: Any) -> tuple[list, bool]:
     """Normalize a validation ``detail`` payload into (errors, truncated).
 
@@ -237,7 +251,7 @@ def build_api_error(
             base_kwargs["message"] = "Resource key already exists"
         return ExternalIdConflict(**base_kwargs)
 
-    if status_code == 422 and error_code == "content_validation_failed":
+    if status_code == 422 and error_code in _CONTENT_VALIDATION_CODES:
         errors, truncated = _validation_errors_from_detail(detail)
         if not message:
             base_kwargs["message"] = "Content validation failed"
diff --git a/tests/test_http_transport.py b/tests/test_http_transport.py
index e465265..6e76c1f 100644
--- a/tests/test_http_transport.py
+++ b/tests/test_http_transport.py
@@ -66,6 +66,45 @@ def test_build_api_error_content_validation_multiple_truncated():
     assert err.errors_truncated is True
 
 
+def test_build_api_error_data_validation_error_is_the_same_failure():
+    """A Flux resource write reports a schema violation with this code.
+
+    It used to fall through to a bare FoxnoseAPIError, so the documented
+    `except ContentValidationFailed` never fired on the most common way to
+    reach a schema violation, and callers had to match on the status code.
+    """
+    detail = {"json_path": "$.title", "message": "required", "validator": "required"}
+    err = _api_error(422, "data_validation_error", detail=detail)
+    assert isinstance(err, ContentValidationFailed)
+    assert err.errors == [detail]
+    assert err.errors_truncated is False
+
+
+def test_build_api_error_data_validation_error_multiple_truncated():
+    detail = {
+        "json_path": "multiple",
+        "errors": [{"json_path": "$.a"}, {"json_path": "$.b"}],
+        "errors_truncated": True,
+        "errors_total": 250,
+    }
+    err = _api_error(422, "data_validation_error", detail=detail)
+    assert isinstance(err, ContentValidationFailed)
+    assert [e["json_path"] for e in err.errors] == ["$.a", "$.b"]
+    assert err.errors_truncated is True
+
+
+def test_build_api_error_data_validation_error_keeps_its_own_code():
+    """Mapped onto a shared class, but the wire code is not rewritten."""
+    err = _api_error(422, "data_validation_error", detail={"json_path": "$.x"})
+    assert err.error_code == "data_validation_error"
+
+
+def test_build_api_error_other_422_still_falls_through():
+    """Only the two validation codes map; 422 alone must not."""
+    err = _api_error(422, "draft_not_supported")
+    assert type(err) is FoxnoseAPIError
+
+
 def test_build_api_error_upstream():
     err = _api_error(502, "upstream_error", body={"error_code": "upstream_error"})
     assert isinstance(err, UpstreamError)