diff --git a/unstract/core/src/unstract/core/cache/redis_client.py b/unstract/core/src/unstract/core/cache/redis_client.py
index ca6c438379..4ef5c507e2 100644
--- a/unstract/core/src/unstract/core/cache/redis_client.py
+++ b/unstract/core/src/unstract/core/cache/redis_client.py
@@ -637,15 +637,33 @@ def _resolve_redis_env(
     # Django cache already makes for this input (apply_url_credentials returns
     # the URL untouched when there is no password), rather than the two
     # disagreeing about a config neither can honour.
+    #
+    # "default" is EXEMPT from the diagnostic, though still dropped. It is Redis's
+    # own built-in user, `AUTH default <pw>` is equivalent to `AUTH <pw>`, and the
+    # chart ships REDIS_USER: default -- so "default with no password" is not a
+    # misconfiguration, it is the absence of ACL usage, which is the normal state
+    # for the in-cluster Redis that has no password at all. Logging it as an error
+    # fired on every default on-prem install: ~20k ERROR lines a day per
+    # namespace, across eight pod types, measured on two staging namespaces. A
+    # NON-default username without a password is still a real mistake and still
+    # reported, because that is the one redis-py turns into an opaque DataError.
+    #
+    # CASE-SENSITIVE, deliberately: Redis ACL usernames are, so `DEFAULT` is a
+    # named user distinct from the built-in `default` and a missing password for
+    # it is a real mistake worth reporting. Whitespace is stripped because
+    # env_chain returns the RAW value on purpose (stripping it there truncated a
+    # password once), so a hand-edited values file can carry padding around a
+    # username that was meant to be the built-in one.
     if username and not password:
-        logger.error(
-            "%sUSER=%r is set but no password is; Redis has no one-argument ACL "
-            "AUTH, so the username is being ignored. Set %sPASSWORD, or clear "
-            "the username.",
-            env_prefix,
-            username,
-            env_prefix,
-        )
+        if username.strip() != "default":
+            logger.error(
+                "%sUSER=%r is set but no password is; Redis has no one-argument "
+                "ACL AUTH, so the username is being ignored. Set %sPASSWORD, or "
+                "clear the username.",
+                env_prefix,
+                username,
+                env_prefix,
+            )
         username = None
     prefixed_db = os.getenv(f"{env_prefix}DB", "").strip()
     generic_db = os.getenv("REDIS_DB", "").strip()
diff --git a/unstract/core/tests/test_redis_client_config.py b/unstract/core/tests/test_redis_client_config.py
index 7411369dfc..168aaa19c9 100644
--- a/unstract/core/tests/test_redis_client_config.py
+++ b/unstract/core/tests/test_redis_client_config.py
@@ -1214,6 +1214,60 @@ def test_a_blank_user_falls_through_to_the_other_spelling(self, monkeypatch):
         assert urlsplit(build_socketio_redis_url()).username == "alice"
 
 
+class TestTheDefaultUserWithoutAPasswordIsNotAnError:
+    """A username without a password is dropped either way; only the DIAGNOSTIC
+    is conditional.
+
+    `default` is Redis's own built-in user and `AUTH default <pw>` is equivalent
+    to `AUTH <pw>`, so `default` with no password is not a misconfiguration -- it
+    is the absence of ACL usage, which is the normal state for the in-cluster
+    Redis, and values.yaml ships REDIS_USER: default. Logging it at ERROR fired
+    on every default on-prem install: ~20k lines a day per namespace across
+    eight pod types, measured on two staging namespaces before this was fixed.
+    """
+
+    @pytest.mark.parametrize("raw", ["default", "  default  "])
+    def test_the_default_user_without_a_password_is_silent(
+        self, monkeypatch, raw, caplog
+    ):
+        monkeypatch.setenv("REDIS_USER", raw)
+        monkeypatch.delenv("REDIS_PASSWORD", raising=False)
+        # Dropped, exactly as a named user would be -- the behaviour is unchanged.
+        assert _resolve_redis_env("REDIS_")["username"] is None
+        # Padding is stripped before the comparison because env_chain returns the
+        # RAW value on purpose, so a hand-edited values file can carry it.
+        assert "ACL AUTH" not in caplog.text
+
+    def test_a_case_distinct_default_still_errors(self, monkeypatch, caplog):
+        """Redis ACL usernames are CASE-SENSITIVE, so `DEFAULT` is a named user
+        distinct from the built-in `default` -- not the exemption, and a missing
+        password for it is a real mistake. Lowercasing the comparison hid this.
+        """
+        monkeypatch.setenv("REDIS_USER", "DEFAULT")
+        monkeypatch.delenv("REDIS_PASSWORD", raising=False)
+        assert _resolve_redis_env("REDIS_")["username"] is None
+        assert "ACL AUTH" in caplog.text
+        assert "DEFAULT" in caplog.text
+
+    def test_a_named_user_without_a_password_still_errors(self, monkeypatch, caplog):
+        """The case the diagnostic exists for, and the one redis-py turns into an
+        opaque `DataError: Invalid input of type: 'NoneType'` on the first command.
+        """
+        monkeypatch.setenv("REDIS_USER", "alice")
+        monkeypatch.delenv("REDIS_PASSWORD", raising=False)
+        assert _resolve_redis_env("REDIS_")["username"] is None
+        assert "ACL AUTH" in caplog.text
+        assert "alice" in caplog.text
+
+    def test_the_default_user_WITH_a_password_is_kept(self, monkeypatch):
+        """The exemption must not reach the supported configuration: `default`
+        plus a password is a real two-argument AUTH and has to survive.
+        """
+        monkeypatch.setenv("REDIS_USER", "default")
+        monkeypatch.setenv("REDIS_PASSWORD", "pw")
+        assert _resolve_redis_env("REDIS_")["username"] == "default"
+
+
 class TestBlankMeansUnsetForTlsToo:
     """The convention has to cover TLS, not just credentials.