diff --git a/api/sys_raft.go b/api/sys_raft.go
index c66ae629e4956..faa62eb3e0f93 100644
--- a/api/sys_raft.go
+++ b/api/sys_raft.go
@@ -1,21 +1,25 @@
 package api
 
 import (
+	"archive/tar"
+	"compress/gzip"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net/http"
+	"sync"
 	"time"
 
+	"github.com/hashicorp/vault/sdk/helper/consts"
 	"github.com/hashicorp/vault/sdk/helper/parseutil"
-
 	"github.com/mitchellh/mapstructure"
-
-	"github.com/hashicorp/vault/sdk/helper/consts"
 )
 
+var ErrIncompleteSnapshot = errors.New("incomplete snapshot, unable to read SHA256SUMS.sealed file")
+
 // RaftJoinResponse represents the response of the raft join API
 type RaftJoinResponse struct {
 	Joined bool `json:"joined"`
@@ -210,11 +214,60 @@ func (c *Sys) RaftSnapshot(snapWriter io.Writer) error {
 		return err
 	}
 
-	_, err = io.Copy(snapWriter, resp.Body)
+	// Make sure that the last file in the archive, SHA256SUMS.sealed, is present
+	// and non-empty.  This is to catch cases where the snapshot failed midstream,
+	// e.g. due to a problem with the seal that prevented encryption of that file.
+	var wg sync.WaitGroup
+	wg.Add(1)
+	var verified bool
+
+	rPipe, wPipe := io.Pipe()
+	dup := io.TeeReader(resp.Body, wPipe)
+	go func() {
+		defer func() {
+			io.Copy(ioutil.Discard, rPipe)
+			rPipe.Close()
+			wg.Done()
+		}()
+
+		uncompressed, err := gzip.NewReader(rPipe)
+		if err != nil {
+			return
+		}
+
+		t := tar.NewReader(uncompressed)
+		var h *tar.Header
+		for {
+			h, err = t.Next()
+			if err != nil {
+				return
+			}
+			if h.Name != "SHA256SUMS.sealed" {
+				continue
+			}
+			var b []byte
+			b, err = ioutil.ReadAll(t)
+			if err != nil || len(b) == 0 {
+				return
+			}
+			verified = true
+			return
+		}
+	}()
+
+	// Copy bytes from dup to snapWriter.  This will have a side effect that
+	// everything read from dup will be written to wPipe.
+	_, err = io.Copy(snapWriter, dup)
+	wPipe.Close()
 	if err != nil {
+		rPipe.CloseWithError(err)
 		return err
 	}
+	wg.Wait()
 
+	if !verified {
+		return ErrIncompleteSnapshot
+	}
 	return nil
 }
 
diff --git a/changelog/12388.txt b/changelog/12388.txt
new file mode 100644
index 0000000000000..f384c90bdb944
--- /dev/null
+++ b/changelog/12388.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+storage/raft: Detect incomplete raft snapshots in api.RaftSnapshot(), and thereby in `vault operator raft snapshot save`.
+```
diff --git a/vault/external_tests/raft/raft_test.go b/vault/external_tests/raft/raft_test.go
index f98b575589fd8..0ab2a3032202c 100644
--- a/vault/external_tests/raft/raft_test.go
+++ b/vault/external_tests/raft/raft_test.go
@@ -4,14 +4,19 @@ import (
 	"bytes"
 	"context"
 	"crypto/md5"
+	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
 
+	vaultseal "github.com/hashicorp/vault/vault/seal"
+
 	"github.com/hashicorp/go-cleanhttp"
 	"github.com/hashicorp/go-uuid"
 	"github.com/hashicorp/vault/api"
@@ -36,6 +41,8 @@ type RaftClusterOpts struct {
 	PhysicalFactoryConfig          map[string]interface{}
 	DisablePerfStandby             bool
 	EnableResponseHeaderRaftNodeID bool
+	NumCores                       int
+	Seal                           vault.Seal
 }
 
 func raftCluster(t testing.TB, ropts *RaftClusterOpts) *vault.TestCluster {
@@ -49,6 +56,7 @@ func raftCluster(t testing.TB, ropts *RaftClusterOpts) *vault.TestCluster {
 		},
 		DisableAutopilot:               !ropts.EnableAutopilot,
 		EnableResponseHeaderRaftNodeID: ropts.EnableResponseHeaderRaftNodeID,
+		Seal:                           ropts.Seal,
 	}
 
 	opts := vault.TestClusterOptions{
@@ -57,6 +65,7 @@ func raftCluster(t testing.TB, ropts *RaftClusterOpts) *vault.TestCluster {
 	opts.InmemClusterLayers = ropts.InmemCluster
 	opts.PhysicalFactoryConfig = ropts.PhysicalFactoryConfig
 	conf.DisablePerformanceStandby = ropts.DisablePerfStandby
+	opts.NumCores = ropts.NumCores
 
 	teststorage.RaftBackendSetup(conf, &opts)
 
@@ -542,6 +551,58 @@ func TestRaft_SnapshotAPI(t *testing.T) {
 	}
 }
 
+func TestRaft_SnapshotAPI_MidstreamFailure(t *testing.T) {
+	// defer goleak.VerifyNone(t)
+	t.Parallel()
+
+	seal, errptr := vaultseal.NewToggleableTestSeal(nil)
+	cluster := raftCluster(t, &RaftClusterOpts{
+		NumCores: 1,
+		Seal:     vault.NewAutoSeal(seal),
+	})
+	defer cluster.Cleanup()
+
+	leaderClient := cluster.Cores[0].Client
+
+	// Write a bunch of keys; if too few, the detection code in api.RaftSnapshot
+	// will never make it into the tar part, it'll fail merely when trying to
+	// decompress the stream.
+	for i := 0; i < 1000; i++ {
+		_, err := leaderClient.Logical().Write(fmt.Sprintf("secret/%d", i), map[string]interface{}{
+			"test": "data",
+		})
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	r, w := io.Pipe()
+	var snap []byte
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	var readErr error
+	go func() {
+		snap, readErr = ioutil.ReadAll(r)
+		wg.Done()
+	}()
+
+	*errptr = errors.New("seal failure")
+	// Take a snapshot
+	err := leaderClient.Sys().RaftSnapshot(w)
+	w.Close()
+	if err == nil || err != api.ErrIncompleteSnapshot {
+		t.Fatalf("expected err=%v, got: %v", api.ErrIncompleteSnapshot, err)
+	}
+	wg.Wait()
+	if len(snap) == 0 && readErr == nil {
+		readErr = errors.New("no bytes read")
+	}
+	if readErr != nil {
+		t.Fatal(readErr)
+	}
+}
+
 func TestRaft_SnapshotAPI_RekeyRotate_Backward(t *testing.T) {
 	type testCase struct {
 		Name               string
diff --git a/vault/seal/seal_testing.go b/vault/seal/seal_testing.go
index e4f4db3cea78d..1a7130b2d0d2c 100644
--- a/vault/seal/seal_testing.go
+++ b/vault/seal/seal_testing.go
@@ -1,6 +1,8 @@
 package seal
 
 import (
+	"context"
+
 	"github.com/hashicorp/go-hclog"
 	wrapping "github.com/hashicorp/go-kms-wrapping"
 )
@@ -22,3 +24,36 @@ func NewTestSeal(opts *TestSealOpts) *Access {
 		OverriddenType: opts.Name,
 	}
 }
+
+func NewToggleableTestSeal(opts *TestSealOpts) (*Access, *error) {
+	if opts == nil {
+		opts = new(TestSealOpts)
+	}
+
+	w := &ToggleableWrapper{Wrapper: wrapping.NewTestWrapper(opts.Secret)}
+	return &Access{
+		Wrapper:        w,
+		OverriddenType: opts.Name,
+	}, &w.Error
+}
+
+type ToggleableWrapper struct {
+	wrapping.Wrapper
+	Error error
+}
+
+func (t ToggleableWrapper) Encrypt(ctx context.Context, bytes []byte, bytes2 []byte) (*wrapping.EncryptedBlobInfo, error) {
+	if t.Error != nil {
+		return nil, t.Error
+	}
+	return t.Wrapper.Encrypt(ctx, bytes, bytes2)
+}
+
+func (t ToggleableWrapper) Decrypt(ctx context.Context, info *wrapping.EncryptedBlobInfo, bytes []byte) ([]byte, error) {
+	if t.Error != nil {
+		return nil, t.Error
+	}
+	return t.Wrapper.Decrypt(ctx, info, bytes)
+}
+
+var _ wrapping.Wrapper = &ToggleableWrapper{}