diff --git a/sdk/azidentity/client_assertion_credential_test.go b/sdk/azidentity/client_assertion_credential_test.go
index 497f48eb2c7f..12d5a8d2c162 100644
--- a/sdk/azidentity/client_assertion_credential_test.go
+++ b/sdk/azidentity/client_assertion_credential_test.go
@@ -65,6 +65,13 @@ func TestClientAssertionCredentialCallbackError(t *testing.T) {
 	}
 }
 
+func TestClientAssertionCredentialNilCallback(t *testing.T) {
+	_, err := NewClientAssertionCredential(fakeTenantID, fakeClientID, nil, nil)
+	if err == nil {
+		t.Fatal("expected an error")
+	}
+}
+
 func TestClientAssertionCredential_Live(t *testing.T) {
 	data, err := os.ReadFile(liveSP.pemPath)
 	if err != nil {
diff --git a/sdk/azidentity/environment_credential_test.go b/sdk/azidentity/environment_credential_test.go
index 3d4b7d2d1e5b..4282615c4791 100644
--- a/sdk/azidentity/environment_credential_test.go
+++ b/sdk/azidentity/environment_credential_test.go
@@ -10,6 +10,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"testing"
@@ -93,6 +94,30 @@ func TestEnvironmentCredential_ClientSecretSet(t *testing.T) {
 	}
 }
 
+func TestEnvironmentCredential_CertificateErrors(t *testing.T) {
+	resetEnvironmentVarsForTest()
+	for _, test := range []struct {
+		name, path string
+	}{
+		{"file doesn't exist", filepath.Join(t.TempDir(), t.Name())},
+		{"invalid file", "testdata/certificate-wrong-key.pem"},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			for k, v := range map[string]string{
+				azureClientID:              fakeClientID,
+				azureClientCertificatePath: test.path,
+				azureTenantID:              fakeTenantID,
+			} {
+				t.Setenv(k, v)
+				_, err := NewEnvironmentCredential(nil)
+				if err == nil {
+					t.Fatal("expected an error")
+				}
+			}
+		})
+	}
+}
+
 func TestEnvironmentCredential_ClientCertificatePathSet(t *testing.T) {
 	resetEnvironmentVarsForTest()
 	err := os.Setenv(azureTenantID, fakeTenantID)
diff --git a/sdk/azidentity/managed_identity_client_test.go b/sdk/azidentity/managed_identity_client_test.go
index aa604b266269..f85b3f1f4d70 100644
--- a/sdk/azidentity/managed_identity_client_test.go
+++ b/sdk/azidentity/managed_identity_client_test.go
@@ -15,6 +15,7 @@ import (
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+	"github.com/Azure/azure-sdk-for-go/sdk/internal/log"
 )
 
 type userAgentValidatingPolicy struct {
@@ -73,3 +74,63 @@ func TestManagedIdentityClient_ApplicationID(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestManagedIdentityClient_UserAssignedIDWarning(t *testing.T) {
+	for _, test := range []struct {
+		name          string
+		createRequest func(*managedIdentityClient) error
+	}{
+		{
+			name: "Azure Arc",
+			createRequest: func(client *managedIdentityClient) error {
+				_, err := client.createAzureArcAuthRequest(context.Background(), client.id, []string{liveTestScope}, "key")
+				return err
+			},
+		},
+		{
+			name: "Cloud Shell",
+			createRequest: func(client *managedIdentityClient) error {
+				_, err := client.createCloudShellAuthRequest(context.Background(), client.id, []string{liveTestScope})
+				return err
+			},
+		},
+		{
+			name: "Service Fabric",
+			createRequest: func(client *managedIdentityClient) error {
+				_, err := client.createServiceFabricAuthRequest(context.Background(), client.id, []string{liveTestScope})
+				return err
+			},
+		},
+	} {
+		for _, id := range []ManagedIDKind{ClientID(fakeClientID), ResourceID(fakeResourceID)} {
+			s := "-ClientID"
+			if id.String() == fakeResourceID {
+				s = "-ResourceID"
+			}
+			t.Run(test.name+s, func(t *testing.T) {
+				msgs := []string{}
+				log.SetListener(func(event log.Event, msg string) {
+					if event == EventAuthentication {
+						msgs = append(msgs, msg)
+					}
+				})
+				client, err := newManagedIdentityClient(&ManagedIdentityCredentialOptions{
+					ID: id,
+				})
+				if err != nil {
+					t.Fatal(err)
+				}
+				err = test.createRequest(client)
+				if err != nil {
+					t.Fatal(err)
+				}
+				for _, msg := range msgs {
+					if strings.Contains(msg, test.name) && strings.Contains(msg, "user-assigned") {
+						return
+					}
+				}
+				t.Fatalf("expected warning about user-assigned ID, got:\n%s", strings.Join(msgs, "\n"))
+			})
+		}
+	}
+}
diff --git a/sdk/azidentity/managed_identity_credential_test.go b/sdk/azidentity/managed_identity_credential_test.go
index 64c6013611a3..e939a6946765 100644
--- a/sdk/azidentity/managed_identity_credential_test.go
+++ b/sdk/azidentity/managed_identity_credential_test.go
@@ -85,6 +85,77 @@ func TestManagedIdentityCredential_AzureArc(t *testing.T) {
 	testGetTokenSuccess(t, cred)
 }
 
+func TestManagedIdentityCredential_AzureArcErrors(t *testing.T) {
+	for k, v := range map[string]string{
+		arcIMDSEndpoint:  "https://localhost",
+		identityEndpoint: "https://localhost",
+	} {
+		t.Setenv(k, v)
+	}
+
+	for _, test := range []struct {
+		challenge, name string
+		statusCode      int
+	}{
+		{name: "no challenge", statusCode: http.StatusUnauthorized},
+		{name: "malformed challenge", challenge: "Basic realm", statusCode: http.StatusUnauthorized},
+		{name: "unexpected status code", statusCode: http.StatusOK},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			srv, close := mock.NewServer(mock.WithTransformAllRequestsToTestServerUrl())
+			defer close()
+			srv.AppendResponse(
+				mock.WithHeader("WWW-Authenticate", test.challenge),
+				mock.WithStatusCode(test.statusCode),
+			)
+			cred, err := NewManagedIdentityCredential(&ManagedIdentityCredentialOptions{
+				ClientOptions: azcore.ClientOptions{Transport: srv},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			_, err = cred.GetToken(context.Background(), testTRO)
+			if err == nil {
+				t.Fatal("expected an error")
+			}
+		})
+	}
+	t.Run("failed to get key", func(t *testing.T) {
+		srv, close := mock.NewServer(mock.WithTransformAllRequestsToTestServerUrl())
+		defer close()
+		srv.SetError(fmt.Errorf("it didn't work"))
+		cred, err := NewManagedIdentityCredential(&ManagedIdentityCredentialOptions{
+			ClientOptions: azcore.ClientOptions{
+				Retry:     policy.RetryOptions{MaxRetries: -1},
+				Transport: srv,
+			},
+		})
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = cred.GetToken(context.Background(), testTRO)
+		if err == nil {
+			t.Fatal("expected an error")
+		}
+	})
+	t.Run("no key file", func(t *testing.T) {
+		srv, close := mock.NewServer(mock.WithTransformAllRequestsToTestServerUrl())
+		defer close()
+		srv.AppendResponse(
+			mock.WithHeader("WWW-Authenticate", "Basic realm="+filepath.Join(t.TempDir(), t.Name())),
+			mock.WithStatusCode(http.StatusUnauthorized),
+		)
+		cred, err := NewManagedIdentityCredential(&ManagedIdentityCredentialOptions{ClientOptions: azcore.ClientOptions{Transport: srv}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = cred.GetToken(context.Background(), testTRO)
+		if err == nil {
+			t.Fatal("expected an error")
+		}
+	})
+}
+
 func TestManagedIdentityCredential_CloudShell(t *testing.T) {
 	validateReq := func(req *http.Request) *http.Response {
 		err := req.ParseForm()
diff --git a/sdk/azidentity/workload_identity_test.go b/sdk/azidentity/workload_identity_test.go
index 20ba3fde5b62..2557a43893d9 100644
--- a/sdk/azidentity/workload_identity_test.go
+++ b/sdk/azidentity/workload_identity_test.go
@@ -119,6 +119,10 @@ func TestWorkloadIdentityCredential(t *testing.T) {
 		t.Fatal(err)
 	}
 	testGetTokenSuccess(t, cred)
+	_, err = cred.GetToken(context.Background(), policy.TokenRequestOptions{Scopes: []string{"scope"}})
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestWorkloadIdentityCredential_Expiration(t *testing.T) {
@@ -186,6 +190,25 @@ func TestTestWorkloadIdentityCredential_IncompleteConfig(t *testing.T) {
 	}
 }
 
+func TestWorkloadIdentityCredential_NoFile(t *testing.T) {
+	for k, v := range map[string]string{
+		azureClientID:           fakeClientID,
+		azureFederatedTokenFile: filepath.Join(t.TempDir(), t.Name()),
+		azureTenantID:           fakeTenantID,
+	} {
+		t.Setenv(k, v)
+	}
+	cred, err := NewWorkloadIdentityCredential(&WorkloadIdentityCredentialOptions{
+		ClientOptions: policy.ClientOptions{Transport: &mockSTS{}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err = cred.GetToken(context.Background(), testTRO); err == nil {
+		t.Fatal("expected an error")
+	}
+}
+
 func TestWorkloadIdentityCredential_Options(t *testing.T) {
 	clientID := "not-" + fakeClientID
 	tenantID := "not-" + fakeTenantID