diff --git a/api/models/enums.py b/api/models/enums.py
index ae05fa242be..d560dca35ac 100644
--- a/api/models/enums.py
+++ b/api/models/enums.py
@@ -214,6 +214,18 @@ class EndUserType(StrEnum):
     SERVICE_API = "service-api"
     TRIGGER = "trigger"
 
+    @classmethod
+    @override
+    def _missing_(cls, value):
+        # Legacy rows persisted the service-api type with an underscore before it
+        # was normalized to the hyphenated value. The
+        # `4f7b2c8d9a10_normalize_legacy_end_user_type` migration rewrites those
+        # rows, but tolerate the old value here as well so an unmigrated end user
+        # keeps loading instead of failing enum validation on every request.
+        if value == "service_api":
+            return cls.SERVICE_API
+        return super()._missing_(value)
+
 
 class DocumentDocType(StrEnum):
     """Document doc_type classification"""
diff --git a/api/tests/unit_tests/models/test_end_user_type.py b/api/tests/unit_tests/models/test_end_user_type.py
index 55a4d35cbb9..222945814b4 100644
--- a/api/tests/unit_tests/models/test_end_user_type.py
+++ b/api/tests/unit_tests/models/test_end_user_type.py
@@ -2,6 +2,9 @@ import ast
 import inspect
 from pathlib import Path
 
+import pytest
+from sqlalchemy.engine.default import DefaultDialect
+
 from models.enums import EndUserType
 from models.model import EndUser
 from models.types import EnumText
@@ -24,6 +27,24 @@ def test_end_user_type_is_plain_persisted_value_enum():
     assert not hasattr(EndUserType, "from_invoke_from")
 
 
+def test_end_user_type_accepts_legacy_service_api_value():
+    # Legacy rows stored the service-api type with an underscore before it was
+    # normalized to the hyphenated value; loading them must not raise. See #38201.
+    assert EndUserType("service_api") is EndUserType.SERVICE_API
+    assert EndUserType("service-api") is EndUserType.SERVICE_API
+
+
+def test_end_user_type_still_rejects_unknown_values():
+    with pytest.raises(ValueError):
+        EndUserType("not-a-real-end-user-type")
+
+
+def test_enum_text_deserializes_legacy_service_api_value():
+    # Exercises the actual column load path that raised for unmigrated rows.
+    column_type = EnumText(EndUserType)
+    assert column_type.process_result_value("service_api", DefaultDialect()) is EndUserType.SERVICE_API
+
+
 def test_end_user_service_creation_methods_accept_end_user_type():
     assert inspect.signature(EndUserService.get_or_create_end_user_by_type).parameters["type"].annotation is EndUserType
     assert inspect.signature(EndUserService.create_end_user_batch).parameters["type"].annotation is EndUserType