diff --git a/dax/controller/client/client.go b/dax/controller/client/client.go
index 9f2adf3a6..38163f5d5 100644
--- a/dax/controller/client/client.go
+++ b/dax/controller/client/client.go
@@ -646,7 +646,7 @@ func (c *Client) RegisterNode(ctx context.Context, node *dax.Node) error {
 
 	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(resp.Body)
-		return errors.Errorf("registration request to %s status code: %d: %s", url, resp.StatusCode, b)
+		return errors.Wrapf(errors.UnmarshalJSON(b), "registration request to %s status code: %d: %s", url, resp.StatusCode, b)
 	}
 
 	return nil
@@ -677,7 +677,7 @@ func (c *Client) CheckInNode(ctx context.Context, node *dax.Node) error {
 
 	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(resp.Body)
-		return errors.Errorf("status code: %d: %s", resp.StatusCode, b)
+		return errors.Wrapf(errors.UnmarshalJSON(b), "status code: %d: %s", resp.StatusCode, b)
 	}
 
 	return nil
diff --git a/dax/controller/controller.go b/dax/controller/controller.go
index c5244a8a2..7ce5376c0 100644
--- a/dax/controller/controller.go
+++ b/dax/controller/controller.go
@@ -267,6 +267,10 @@ func (c *Controller) RegisterNode(ctx context.Context, n *dax.Node) error {
 // from its list (perhaps due to a network fault) and therefore the node needs
 // to be re-registered.
 func (c *Controller) CheckInNode(ctx context.Context, n *dax.Node) error {
+	if n == nil || n.Address == "" {
+		return NewErrNodeKeyInvalid("")
+	}
+
 	tx, err := c.BoltDB.BeginTx(ctx, false)
 	if err != nil {
 		return errors.Wrap(err, "beginning tx")
diff --git a/dax/controller/http/handler.go b/dax/controller/http/handler.go
index ccda6e881..6071c89e5 100644
--- a/dax/controller/http/handler.go
+++ b/dax/controller/http/handler.go
@@ -615,7 +615,7 @@ func (s *server) postRegisterNode(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := s.controller.RegisterNode(ctx, node); err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		http.Error(w, errors.MarshalJSON(err), http.StatusBadRequest)
 		return
 	}
 
@@ -700,7 +700,7 @@ func (s *server) postCheckInNode(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := s.controller.CheckInNode(ctx, node); err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		http.Error(w, errors.MarshalJSON(err), http.StatusBadRequest)
 		return
 	}
 
diff --git a/dax/test/dax/dax_test.go b/dax/test/dax/dax_test.go
index d3536183f..886c2247f 100644
--- a/dax/test/dax/dax_test.go
+++ b/dax/test/dax/dax_test.go
@@ -13,10 +13,12 @@ import (
 
 	featurebase "github.com/featurebasedb/featurebase/v3"
 	"github.com/featurebasedb/featurebase/v3/dax"
+	"github.com/featurebasedb/featurebase/v3/dax/controller"
 	controllerclient "github.com/featurebasedb/featurebase/v3/dax/controller/client"
 	queryerclient "github.com/featurebasedb/featurebase/v3/dax/queryer/client"
 	"github.com/featurebasedb/featurebase/v3/dax/server"
 	"github.com/featurebasedb/featurebase/v3/dax/server/test"
+	"github.com/featurebasedb/featurebase/v3/errors"
 	"github.com/featurebasedb/featurebase/v3/logger"
 	"github.com/featurebasedb/featurebase/v3/sql3/test/defs"
 	goerrors "github.com/pkg/errors"
@@ -706,6 +708,46 @@ func TestDAXIntegration(t *testing.T) {
 			assert.Equal(t, partitions2, nodes[2].Partitions)
 		}
 	})
+
+	t.Run("HTTPError", func(t *testing.T) {
+		mc := test.MustRunManagedCommand(t)
+		defer mc.Close()
+
+		svcmgr := mc.Manage()
+		ctx := context.Background()
+
+		t.Run("controller", func(t *testing.T) {
+			// Set up Controller client.
+			client := newWrappedControllerClient(controllerclient.New(svcmgr.Controller.Address(), svcmgr.Logger))
+
+			t.Run("Registrar", func(t *testing.T) {
+				t.Run("RegisterNode", func(t *testing.T) {
+					node := &dax.Node{}
+					err := client.RegisterNode(ctx, node)
+					if assert.Error(t, err) {
+						assert.True(t, errors.Is(err, controller.ErrCodeNodeKeyInvalid))
+					}
+				})
+				t.Run("CheckInNode", func(t *testing.T) {
+					node := &dax.Node{}
+					err := client.CheckInNode(ctx, node)
+					if assert.Error(t, err) {
+						assert.True(t, errors.Is(err, controller.ErrCodeNodeKeyInvalid))
+					}
+				})
+			})
+
+			t.Run("Schemar", func(t *testing.T) {
+				t.Run("CreateDatabase", func(t *testing.T) {
+					log.Printf("client: %+v", client)
+					err := client.CreateDatabase(ctx, qdb)
+					if assert.Error(t, err) {
+						assert.True(t, errors.Is(err, controller.ErrCodeNodeKeyInvalid))
+					}
+				})
+			})
+		})
+	})
 }
 
 func dirIsEmpty(t *testing.T, name string) bool {
diff --git a/dax/test/dax/wrappers_test.go b/dax/test/dax/wrappers_test.go
new file mode 100644
index 000000000..a0b4913fa
--- /dev/null
+++ b/dax/test/dax/wrappers_test.go
@@ -0,0 +1,65 @@
+package dax_test
+
+import (
+	"context"
+
+	"github.com/featurebasedb/featurebase/v3/dax"
+	"github.com/featurebasedb/featurebase/v3/dax/computer"
+	controllerclient "github.com/featurebasedb/featurebase/v3/dax/controller/client"
+)
+
+var _ computer.Registrar = (*wrappedControllerClient)(nil)
+
+//var _ dax.Schemar = (*wrappedControllerClient)(nil)
+
+// wrappedControllerClient is a wrapper around the controller client which we
+// use in tests to ensure that all of the methods for the computer.Registrar
+// interface are covered by these tests. The idea being that if someone modifes
+// the interface to include a new `Foo()` method, this test will no longer
+// compile, and the developer will be directected here to add the appropriate
+// tests. There's probably a more automated way to do this wil the `reflect`
+// package, but that seems overly compilicated right now.
+type wrappedControllerClient struct {
+	cli *controllerclient.Client
+	dax.Schemar
+}
+
+func newWrappedControllerClient(cli *controllerclient.Client) *wrappedControllerClient {
+	return &wrappedControllerClient{
+		cli:     cli,
+		Schemar: dax.NewNopSchemar(),
+	}
+}
+
+func (w *wrappedControllerClient) RegisterNode(ctx context.Context, node *dax.Node) error {
+	return w.cli.RegisterNode(ctx, node)
+}
+
+func (w *wrappedControllerClient) CheckInNode(ctx context.Context, node *dax.Node) error {
+	return w.cli.CheckInNode(ctx, node)
+}
+
+// Schemar
+
+/*
+func (w *wrappedControllerClient) 	CreateDatabase(context.Context, *QualifiedDatabase) error
+func (w *wrappedControllerClient) 	DropDatabase(context.Context, QualifiedDatabaseID) error
+
+	DatabaseByName(ctx context.Context, orgID OrganizationID, dbname DatabaseName) (*QualifiedDatabase, error)
+	DatabaseByID(ctx context.Context, qdbid QualifiedDatabaseID) (*QualifiedDatabase, error)
+
+	SetDatabaseOption(ctx context.Context, qdbid QualifiedDatabaseID, option string, value string) error
+
+	Databases(context.Context, OrganizationID, ...DatabaseID) ([]*QualifiedDatabase, error)
+
+	CreateTable(ctx context.Context, qtbl *QualifiedTable) error
+	DropTable(ctx context.Context, qtid QualifiedTableID) error
+
+	TableByName(ctx context.Context, qdbid QualifiedDatabaseID, tname TableName) (*QualifiedTable, error)
+	TableByID(ctx context.Context, qtid QualifiedTableID) (*QualifiedTable, error)
+
+	Tables(ctx context.Context, qdbid QualifiedDatabaseID, tids ...TableID) ([]*QualifiedTable, error)
+
+	CreateField(ctx context.Context, qtid QualifiedTableID, fld *Field) error
+	DropField(ctx context.Context, qtid QualifiedTableID, fname FieldName) error
+*/