diff --git a/cmd/pinniped/cmd/kubeconfig_test.go b/cmd/pinniped/cmd/kubeconfig_test.go
index 79017e852..615c3db8e 100644
--- a/cmd/pinniped/cmd/kubeconfig_test.go
+++ b/cmd/pinniped/cmd/kubeconfig_test.go
@@ -1749,7 +1749,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -1819,7 +1818,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -1883,7 +1881,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -1950,7 +1947,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2033,7 +2029,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2116,7 +2111,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2201,7 +2195,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2281,7 +2274,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-sso
 					current-context: kind-context-sso
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-sso
 					  user:
@@ -2400,7 +2392,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2509,7 +2500,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2586,7 +2576,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2665,7 +2654,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2742,7 +2730,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2815,7 +2802,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2895,7 +2881,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -2982,7 +2967,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3070,7 +3054,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3158,7 +3141,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3236,7 +3218,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3319,7 +3300,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3385,7 +3365,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3446,7 +3425,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3507,7 +3485,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3569,7 +3546,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3631,7 +3607,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3692,7 +3667,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3752,7 +3726,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
@@ -3818,7 +3791,6 @@ func TestGetKubeconfig(t *testing.T) {
 					  name: kind-context-pinniped
 					current-context: kind-context-pinniped
 					kind: Config
-					preferences: {}
 					users:
 					- name: kind-user-pinniped
 					  user:
diff --git a/cmd/pinniped/cmd/whoami_test.go b/cmd/pinniped/cmd/whoami_test.go
index c38af8528..fba4d51ac 100644
--- a/cmd/pinniped/cmd/whoami_test.go
+++ b/cmd/pinniped/cmd/whoami_test.go
@@ -130,9 +130,7 @@ func TestWhoami(t *testing.T) {
 				{
 				  "kind": "WhoAmIRequest",
 				  "apiVersion": "identity.concierge.pinniped.dev/v1alpha1",
-				  "metadata": {
-				    "creationTimestamp": null
-				  },
+				  "metadata": {},
 				  "spec": {},
 				  "status": {
 				    "kubernetesUserInfo": {
@@ -154,9 +152,7 @@ func TestWhoami(t *testing.T) {
 				{
 				  "kind": "WhoAmIRequest",
 				  "apiVersion": "identity.concierge.tuna.io/v1alpha1",
-				  "metadata": {
-				    "creationTimestamp": null
-				  },
+				  "metadata": {},
 				  "spec": {},
 				  "status": {
 				    "kubernetesUserInfo": {
@@ -177,8 +173,7 @@ func TestWhoami(t *testing.T) {
 			wantStdout: here.Doc(`
 				apiVersion: identity.concierge.pinniped.dev/v1alpha1
 				kind: WhoAmIRequest
-				metadata:
-				  creationTimestamp: null
+				metadata: {}
 				spec: {}
 				status:
 				  kubernetesUserInfo:
@@ -195,8 +190,7 @@ func TestWhoami(t *testing.T) {
 			wantStdout: here.Doc(`
 				apiVersion: identity.concierge.tuna.io/v1alpha1
 				kind: WhoAmIRequest
-				metadata:
-				  creationTimestamp: null
+				metadata: {}
 				spec: {}
 				status:
 				  kubernetesUserInfo:
diff --git a/internal/concierge/impersonator/impersonator_test.go b/internal/concierge/impersonator/impersonator_test.go
index ef62ed9a6..09c3409f7 100644
--- a/internal/concierge/impersonator/impersonator_test.go
+++ b/internal/concierge/impersonator/impersonator_test.go
@@ -769,23 +769,23 @@ func TestImpersonator(t *testing.T) {
 			},
 		},
 		{
-			name:       "header canonicalization future UID header", // no longer future as it exists in Kube v1.22
+			name:       "header canonicalization of UID header, starting in Kube v1.22",
 			clientCert: newClientCert(t, ca, "test-username", []string{"test-group1", "test-group2"}),
 			clientMutateHeaders: func(header http.Header) {
 				header["imPerSonaTE-uid"] = []string{"007"}
 			},
-			wantError: `an error on the server ("Internal Server Error: \"/api/v1/namespaces\": requested [{UID  007  authentication.k8s.io/v1  }] without impersonating a user") has prevented the request from succeeding (get namespaces)`,
+			wantError: `requested [{UID  007  authentication.k8s.io/v1  }] without impersonating a user`,
 			wantAuthorizerAttributes: func(_credentialID string) []authorizer.AttributesRecord {
 				return []authorizer.AttributesRecord{}
 			},
 		},
 		{
-			name:       "UID header starting in Kube v1.22",
+			name:       "UID header, starting in Kube v1.22",
 			clientCert: newClientCert(t, ca, "test-username", []string{"test-group1", "test-group2"}),
 			clientMutateHeaders: func(header http.Header) {
 				header["Impersonate-Uid"] = []string{"008"}
 			},
-			wantError: `an error on the server ("Internal Server Error: \"/api/v1/namespaces\": requested [{UID  008  authentication.k8s.io/v1  }] without impersonating a user") has prevented the request from succeeding (get namespaces)`,
+			wantError: `requested [{UID  008  authentication.k8s.io/v1  }] without impersonating a user`,
 			wantAuthorizerAttributes: func(_credentialID string) []authorizer.AttributesRecord {
 				return []authorizer.AttributesRecord{}
 			},
diff --git a/internal/registry/clientsecretrequest/rest_test.go b/internal/registry/clientsecretrequest/rest_test.go
index c1ee55ad2..d2ef284a2 100644
--- a/internal/registry/clientsecretrequest/rest_test.go
+++ b/internal/registry/clientsecretrequest/rest_test.go
@@ -1,4 +1,4 @@
-// Copyright 2022-2024 the Pinniped contributors. All Rights Reserved.
+// Copyright 2022-2025 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 package clientsecretrequest
@@ -161,7 +161,7 @@ func TestCreate(t *testing.T) {
 			wantErrStatus: &metav1.Status{
 				Status: metav1.StatusFailure,
 				Message: `OIDCClientSecretRequest.clientsecret.supervisor.pinniped.dev "client.oauth.pinniped.dev-some-client-name" ` +
-					`is invalid: dryRun: Unsupported value: []string{"stuff"}`,
+					`is invalid: dryRun: Unsupported value: ["stuff"]`,
 				Reason: metav1.StatusReasonInvalid,
 				Code:   http.StatusUnprocessableEntity,
 				Details: &metav1.StatusDetails{
@@ -170,7 +170,7 @@ func TestCreate(t *testing.T) {
 					Name:  "client.oauth.pinniped.dev-some-client-name",
 					Causes: []metav1.StatusCause{{
 						Type:    "FieldValueNotSupported",
-						Message: "Unsupported value: []string{\"stuff\"}",
+						Message: `Unsupported value: ["stuff"]`,
 						Field:   "dryRun",
 					}},
 				},
diff --git a/internal/registry/credentialrequest/rest_test.go b/internal/registry/credentialrequest/rest_test.go
index 948a605ab..491502a86 100644
--- a/internal/registry/credentialrequest/rest_test.go
+++ b/internal/registry/credentialrequest/rest_test.go
@@ -597,7 +597,7 @@ func TestCreate(t *testing.T) {
 				})
 
 			requireAPIError(t, response, err, apierrors.IsInvalid,
-				`.pinniped.dev "request name" is invalid: dryRun: Unsupported value: []string{"some dry run flag"}`)
+				`.pinniped.dev "request name" is invalid: dryRun: Unsupported value: ["some dry run flag"]`)
 		})
 
 		it("CreateFailsWhenNamespaceIsNotEmpty", func() {
diff --git a/internal/registry/whoamirequest/rest_test.go b/internal/registry/whoamirequest/rest_test.go
index 77f9a53ee..9ffcaafbd 100644
--- a/internal/registry/whoamirequest/rest_test.go
+++ b/internal/registry/whoamirequest/rest_test.go
@@ -1,4 +1,4 @@
-// Copyright 2021-2024 the Pinniped contributors. All Rights Reserved.
+// Copyright 2021-2025 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 package whoamirequest
@@ -92,7 +92,7 @@ func TestCreate(t *testing.T) {
 				options:          &metav1.CreateOptions{DryRun: []string{"stuff"}},
 			},
 			want:    nil,
-			wantErr: `SomeKind.identity.concierge.pinniped.dev "some-name" is invalid: dryRun: Unsupported value: []string{"stuff"}`,
+			wantErr: `SomeKind.identity.concierge.pinniped.dev "some-name" is invalid: dryRun: Unsupported value: ["stuff"]`,
 		},
 		{
 			name: "bad namespace",
diff --git a/pkg/conciergeclient/conciergeclient_test.go b/pkg/conciergeclient/conciergeclient_test.go
index edc1148c6..98195d622 100644
--- a/pkg/conciergeclient/conciergeclient_test.go
+++ b/pkg/conciergeclient/conciergeclient_test.go
@@ -1,4 +1,4 @@
-// Copyright 2020-2024 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2025 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 package conciergeclient
@@ -229,9 +229,7 @@ func TestExchangeToken(t *testing.T) {
 				`{
 				  "kind": "TokenCredentialRequest",
 				  "apiVersion": "login.concierge.pinniped.dev/v1alpha1",
-				  "metadata": {
-					"creationTimestamp": null
-				  },
+				  "metadata": {},
 				  "spec": {
 					"token": "test-token",
 					"authenticator": {