diff --git a/src/launchpad/artifact_processor.py b/src/launchpad/artifact_processor.py
index 3a1e2384..ebbc4e94 100644
--- a/src/launchpad/artifact_processor.py
+++ b/src/launchpad/artifact_processor.py
@@ -34,6 +34,7 @@
 from launchpad.artifacts.artifact_factory import ArtifactFactory
 from launchpad.constants import (
     ArtifactType,
+    InstallableAppErrorCode,
     PreprodFeature,
     ProcessingErrorCode,
     ProcessingErrorMessage,
@@ -331,9 +332,16 @@ def _do_distribution(
             with apk.raw_file() as f:
                 self._sentry_client.upload_installable_app(organization_id, project_id, artifact_id, f)
         else:
-            # TODO(EME-422): Should call _update_artifact_error here once we
-            # support setting errors just for build.
-            logger.error(f"BUILD_DISTRIBUTION failed for {artifact_id} (project: {project_id}, org: {organization_id})")
+            logger.error(f"BUILD_DISTRIBUTION failed for {artifact_id}: unsupported artifact type")
+            try:
+                self._sentry_client.update_distribution_error(
+                    org=organization_id,
+                    artifact_id=artifact_id,
+                    error_code=InstallableAppErrorCode.PROCESSING_ERROR.value,
+                    error_message="unsupported artifact type",
+                )
+            except Exception:
+                logger.exception(f"Failed to update distribution error for artifact {artifact_id}")
 
     def _do_size(
         self,
diff --git a/src/launchpad/constants.py b/src/launchpad/constants.py
index 4eb84c0f..8f449417 100644
--- a/src/launchpad/constants.py
+++ b/src/launchpad/constants.py
@@ -32,6 +32,14 @@ class PreprodFeature(Enum):
     BUILD_DISTRIBUTION = "build_distribution"
 
 
+# Matches InstallableApp.ErrorCode in sentry
+class InstallableAppErrorCode(Enum):
+    UNKNOWN = 0
+    NO_QUOTA = 1
+    SKIPPED = 2
+    PROCESSING_ERROR = 3
+
+
 # Health check threshold - consider unhealthy if file not touched in 60 seconds
 HEALTHCHECK_MAX_AGE_SECONDS = 60.0
 
diff --git a/src/launchpad/sentry_client.py b/src/launchpad/sentry_client.py
index e2581ecc..24d03872 100644
--- a/src/launchpad/sentry_client.py
+++ b/src/launchpad/sentry_client.py
@@ -252,6 +252,24 @@ def update_artifact(self, org: str, project: str, artifact_id: str, data: Dict[s
         endpoint = f"/api/0/internal/{org}/{project}/files/preprodartifacts/{artifact_id}/update/"
         return self._make_json_request("PUT", endpoint, UpdateResponse, data=data)
 
+    def update_distribution_error(self, org: str, artifact_id: str, error_code: int, error_message: str) -> None:
+        """Report distribution error via the dedicated distribution endpoint."""
+        endpoint = f"/api/0/organizations/{org}/preprodartifacts/{artifact_id}/distribution/"
+        url = self._build_url(endpoint)
+        body = json.dumps({"error_code": error_code, "error_message": error_message}).encode("utf-8")
+
+        logger.debug(f"PUT {url}")
+        response = self.session.request(
+            method="PUT",
+            url=url,
+            data=body,
+            auth=self.auth,
+            timeout=30,
+        )
+
+        if response.status_code != 200:
+            raise SentryClientError(response=response)
+
     def upload_size_analysis_file(
         self,
         org: str,
diff --git a/tests/unit/artifacts/test_artifact_processor.py b/tests/unit/artifacts/test_artifact_processor.py
index bdd18b2e..1d668100 100644
--- a/tests/unit/artifacts/test_artifact_processor.py
+++ b/tests/unit/artifacts/test_artifact_processor.py
@@ -6,7 +6,9 @@
 )
 
 from launchpad.artifact_processor import ArtifactProcessor
+from launchpad.artifacts.artifact import Artifact
 from launchpad.constants import (
+    InstallableAppErrorCode,
     ProcessingErrorCode,
     ProcessingErrorMessage,
 )
@@ -137,6 +139,25 @@ def test_processing_error_message_enum_values(self):
         assert ProcessingErrorMessage.SIZE_ANALYSIS_FAILED.value == "Failed to perform size analysis"
         assert ProcessingErrorMessage.UNKNOWN_ERROR.value == "An unknown error occurred"
 
+    def test_do_distribution_unknown_artifact_type_reports_error(self):
+        mock_sentry_client = Mock(spec=SentryClient)
+        mock_sentry_client.update_distribution_error.return_value = None
+        self.processor._sentry_client = mock_sentry_client
+
+        unknown_artifact = Mock(spec=Artifact)
+        mock_info = Mock()
+
+        self.processor._do_distribution(
+            "test-org-id", "test-project-id", "test-artifact-id", unknown_artifact, mock_info
+        )
+
+        mock_sentry_client.update_distribution_error.assert_called_once_with(
+            org="test-org-id",
+            artifact_id="test-artifact-id",
+            error_code=InstallableAppErrorCode.PROCESSING_ERROR.value,
+            error_message="unsupported artifact type",
+        )
+
 
 class TestArtifactProcessorMessageHandling:
     """Test message processing functionality in ArtifactProcessor."""