diff --git a/errorcode_string.go b/errorcode_string.go
new file mode 100644
index 0000000..08b3b3d
--- /dev/null
+++ b/errorcode_string.go
@@ -0,0 +1,51 @@
+// Code generated by "stringer -type=ErrorCode"; DO NOT EDIT.
+
+package vz
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ErrorInternal-1]
+	_ = x[ErrorInvalidVirtualMachineConfiguration-2]
+	_ = x[ErrorInvalidVirtualMachineState-3]
+	_ = x[ErrorInvalidVirtualMachineStateTransition-4]
+	_ = x[ErrorInvalidDiskImage-5]
+	_ = x[ErrorVirtualMachineLimitExceeded-6]
+	_ = x[ErrorNetworkError-7]
+	_ = x[ErrorOutOfDiskSpace-8]
+	_ = x[ErrorOperationCancelled-9]
+	_ = x[ErrorNotSupported-10]
+	_ = x[ErrorRestoreImageCatalogLoadFailed-10001]
+	_ = x[ErrorInvalidRestoreImageCatalog-10002]
+	_ = x[ErrorNoSupportedRestoreImagesInCatalog-10003]
+	_ = x[ErrorRestoreImageLoadFailed-10004]
+	_ = x[ErrorInvalidRestoreImage-10005]
+	_ = x[ErrorInstallationRequiresUpdate-10006]
+	_ = x[ErrorInstallationFailed-10007]
+}
+
+const (
+	_ErrorCode_name_0 = "ErrorInternalErrorInvalidVirtualMachineConfigurationErrorInvalidVirtualMachineStateErrorInvalidVirtualMachineStateTransitionErrorInvalidDiskImageErrorVirtualMachineLimitExceededErrorNetworkErrorErrorOutOfDiskSpaceErrorOperationCancelledErrorNotSupported"
+	_ErrorCode_name_1 = "ErrorRestoreImageCatalogLoadFailedErrorInvalidRestoreImageCatalogErrorNoSupportedRestoreImagesInCatalogErrorRestoreImageLoadFailedErrorInvalidRestoreImageErrorInstallationRequiresUpdateErrorInstallationFailed"
+)
+
+var (
+	_ErrorCode_index_0 = [...]uint8{0, 13, 52, 83, 124, 145, 177, 194, 213, 236, 253}
+	_ErrorCode_index_1 = [...]uint8{0, 34, 65, 103, 130, 154, 185, 208}
+)
+
+func (i ErrorCode) String() string {
+	switch {
+	case 1 <= i && i <= 10:
+		i -= 1
+		return _ErrorCode_name_0[_ErrorCode_index_0[i]:_ErrorCode_index_0[i+1]]
+	case 10001 <= i && i <= 10007:
+		i -= 10001
+		return _ErrorCode_name_1[_ErrorCode_index_1[i]:_ErrorCode_index_1[i+1]]
+	default:
+		return "ErrorCode(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}
diff --git a/vzerror.go b/vzerror.go
new file mode 100644
index 0000000..8298269
--- /dev/null
+++ b/vzerror.go
@@ -0,0 +1,77 @@
+package vz
+
+// Error type returned by the Virtualization framework.
+// The NSError domain is VZErrorDomain, the code is one of the ErrorCode constants.
+//
+//go:generate stringer -type=ErrorCode
+type ErrorCode int
+
+const (
+	// ErrorInternal is an internal error such as the virtual machine unexpectedly stopping.
+	ErrorInternal ErrorCode = 1 + iota
+
+	// ErrorInvalidVirtualMachineConfiguration represents invalid machine configuration.
+	ErrorInvalidVirtualMachineConfiguration
+
+	// ErrorInvalidVirtualMachineState represents API used with a machine in the wrong state
+	// (e.g. interacting with a machine before it is running).
+	ErrorInvalidVirtualMachineState
+
+	// ErrorInvalidVirtualMachineStateTransition is invalid change of state
+	// (e.g. pausing a virtual machine that is not started).
+	ErrorInvalidVirtualMachineStateTransition
+
+	// ErrorInvalidDiskImage represents unrecognized disk image format or invalid disk image.
+	ErrorInvalidDiskImage
+
+	// ErrorVirtualMachineLimitExceeded represents the running virtual machine limit was exceeded.
+	// Available from macOS 12.0 and above.
+	ErrorVirtualMachineLimitExceeded
+
+	// ErrorNetworkError represents network error occurred.
+	// Available from macOS 13.0 and above.
+	ErrorNetworkError
+
+	// ErrorOutOfDiskSpace represents machine ran out of disk space.
+	// Available from macOS 13.0 and above.
+	ErrorOutOfDiskSpace
+
+	// ErrorOperationCancelled represents the operation was cancelled.
+	// Available from macOS 13.0 and above.
+	ErrorOperationCancelled
+
+	// ErrorNotSupported represents the operation is not supported.
+	// Available from macOS 13.0 and above.
+	ErrorNotSupported
+)
+
+/* macOS installation errors. */
+const (
+	// ErrorRestoreImageCatalogLoadFailed represents the restore image catalog failed to load.
+	// Available from macOS 13.0 and above.
+	ErrorRestoreImageCatalogLoadFailed ErrorCode = 10001 + iota
+
+	// ErrorInvalidRestoreImageCatalog represents the restore image catalog is invalid.
+	// Available from macOS 13.0 and above.
+	ErrorInvalidRestoreImageCatalog
+
+	// ErrorNoSupportedRestoreImagesInCatalog represents the restore image catalog has no supported restore images.
+	// Available from macOS 13.0 and above.
+	ErrorNoSupportedRestoreImagesInCatalog
+
+	// ErrorRestoreImageLoadFailed represents the restore image failed to load.
+	// Available from macOS 13.0 and above.
+	ErrorRestoreImageLoadFailed
+
+	// ErrorInvalidRestoreImage represents the restore image is invalid.
+	// Available from macOS 13.0 and above.
+	ErrorInvalidRestoreImage
+
+	// ErrorInstallationRequiresUpdate represents a software update is required to complete the installation.
+	// Available from macOS 13.0 and above.
+	ErrorInstallationRequiresUpdate
+
+	// ErrorInstallationFailed is an error occurred during installation.
+	// Available from macOS 13.0 and above.
+	ErrorInstallationFailed
+)
diff --git a/vzerror_test.go b/vzerror_test.go
new file mode 100644
index 0000000..4acfad8
--- /dev/null
+++ b/vzerror_test.go
@@ -0,0 +1,106 @@
+package vz_test
+
+import (
+	"testing"
+
+	"github.com/Code-Hex/vz/v2"
+)
+
+func TestErrorCodeString(t *testing.T) {
+	t.Run("fundamental error code", func(t *testing.T) {
+		cases := []struct {
+			code vz.ErrorCode
+			want string
+		}{
+			{
+				code: vz.ErrorInternal,
+				want: "ErrorInternal",
+			},
+			{
+				code: vz.ErrorInvalidVirtualMachineConfiguration,
+				want: "ErrorInvalidVirtualMachineConfiguration",
+			},
+			{
+				code: vz.ErrorInvalidVirtualMachineState,
+				want: "ErrorInvalidVirtualMachineState",
+			},
+			{
+				code: vz.ErrorInvalidVirtualMachineStateTransition,
+				want: "ErrorInvalidVirtualMachineStateTransition",
+			},
+			{
+				code: vz.ErrorInvalidDiskImage,
+				want: "ErrorInvalidDiskImage",
+			},
+			{
+				code: vz.ErrorVirtualMachineLimitExceeded,
+				want: "ErrorVirtualMachineLimitExceeded",
+			},
+			{
+				code: vz.ErrorNetworkError,
+				want: "ErrorNetworkError",
+			},
+
+			{
+				code: vz.ErrorOutOfDiskSpace,
+				want: "ErrorOutOfDiskSpace",
+			},
+			{
+				code: vz.ErrorOperationCancelled,
+				want: "ErrorOperationCancelled",
+			},
+			{
+				code: vz.ErrorNotSupported,
+				want: "ErrorNotSupported",
+			},
+		}
+		for _, tc := range cases {
+			got := tc.code.String()
+			if tc.want != got {
+				t.Fatalf("want %q but got %q", tc.want, got)
+			}
+		}
+	})
+
+	t.Run("macOS installation", func(t *testing.T) {
+		cases := []struct {
+			code vz.ErrorCode
+			want string
+		}{
+			{
+				code: vz.ErrorRestoreImageCatalogLoadFailed,
+				want: "ErrorRestoreImageCatalogLoadFailed",
+			},
+			{
+				code: vz.ErrorInvalidRestoreImageCatalog,
+				want: "ErrorInvalidRestoreImageCatalog",
+			},
+			{
+				code: vz.ErrorNoSupportedRestoreImagesInCatalog,
+				want: "ErrorNoSupportedRestoreImagesInCatalog",
+			},
+			{
+				code: vz.ErrorRestoreImageLoadFailed,
+				want: "ErrorRestoreImageLoadFailed",
+			},
+			{
+				code: vz.ErrorInvalidRestoreImage,
+				want: "ErrorInvalidRestoreImage",
+			},
+			{
+				code: vz.ErrorInstallationRequiresUpdate,
+				want: "ErrorInstallationRequiresUpdate",
+			},
+			{
+				code: vz.ErrorInstallationFailed,
+				want: "ErrorInstallationFailed",
+			},
+		}
+		for _, tc := range cases {
+			got := tc.code.String()
+			if tc.want != got {
+				t.Fatalf("want %q but got %q", tc.want, got)
+			}
+		}
+	})
+}