diff --git a/copy.go b/copy.go
index 79feda53..0e0d5d85 100644
--- a/copy.go
+++ b/copy.go
@@ -284,6 +284,8 @@ func mountOrCopyNode(ctx context.Context, src content.ReadOnlyStorage, dst conte
 
 	// Only care to mount blobs
 	if descriptor.IsManifest(desc) {
+		// mountOrCopyNode might never be called with a Manifest based on how copyGraph() is currently implemented
+		// but it is safer to handle all cases so we keep this here
 		return copyNode(ctx, src, dst, desc, opts)
 	}
 
diff --git a/copy_test.go b/copy_test.go
index 2343d18f..9a067e52 100644
--- a/copy_test.go
+++ b/copy_test.go
@@ -1456,7 +1456,7 @@ func TestCopyGraph_WithOptions(t *testing.T) {
 			},
 		}
 		if err := oras.CopyGraph(ctx, src, dst, root, opts); err != nil {
-			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, errdef.ErrSizeExceedsLimit)
+			t.Fatalf("CopyGraph() error = %v", err)
 		}
 
 		if got, expected := dst.numExists.Load(), int64(7); got != expected {
@@ -1515,7 +1515,7 @@ func TestCopyGraph_WithOptions(t *testing.T) {
 			return []string{"source"}, nil
 		}
 		if err := oras.CopyGraph(ctx, src, dst, root, opts); err != nil {
-			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, errdef.ErrSizeExceedsLimit)
+			t.Fatalf("CopyGraph() error = %v", err)
 		}
 
 		if got, expected := dst.numExists.Load(), int64(7); got != expected {
@@ -1590,7 +1590,7 @@ func TestCopyGraph_WithOptions(t *testing.T) {
 			return []string{"source"}, nil
 		}
 		if err := oras.CopyGraph(ctx, src, dst, root, opts); err != nil {
-			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, errdef.ErrSizeExceedsLimit)
+			t.Fatalf("CopyGraph() error = %v", err)
 		}
 
 		if got, expected := dst.numExists.Load(), int64(7); got != expected {
@@ -1679,7 +1679,7 @@ func TestCopyGraph_WithOptions(t *testing.T) {
 			return []string{"missing/the/data", "source"}, nil
 		}
 		if err := oras.CopyGraph(ctx, src, dst, root, opts); err != nil {
-			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, errdef.ErrSizeExceedsLimit)
+			t.Fatalf("CopyGraph() error = %v", err)
 		}
 
 		if got, expected := dst.numExists.Load(), int64(7); got != expected {
@@ -1709,6 +1709,134 @@ func TestCopyGraph_WithOptions(t *testing.T) {
 			t.Errorf("count(PostCopy()) = %d, want %d", got, expected)
 		}
 	})
+
+	t.Run("MountFrom empty sourceRepositories", func(t *testing.T) {
+		root = descs[6]
+		dst := &countingStorage{storage: cas.NewMemory()}
+		opts = oras.CopyGraphOptions{}
+		var numMountFrom atomic.Int64
+		opts.MountFrom = func(ctx context.Context, desc ocispec.Descriptor) ([]string, error) {
+			numMountFrom.Add(1)
+			return nil, nil
+		}
+		if err := oras.CopyGraph(ctx, src, dst, root, opts); err != nil {
+			t.Fatalf("CopyGraph() error = %v", err)
+		}
+
+		if got, expected := dst.numExists.Load(), int64(7); got != expected {
+			t.Errorf("count(Exists()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numFetch.Load(), int64(0); got != expected {
+			t.Errorf("count(Fetch()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numPush.Load(), int64(7); got != expected {
+			t.Errorf("count(Push()) = %d, want %d", got, expected)
+		}
+		if got, expected := numMountFrom.Load(), int64(4); got != expected {
+			t.Errorf("count(MountFrom()) = %d, want %d", got, expected)
+		}
+	})
+
+	t.Run("MountFrom error", func(t *testing.T) {
+		root = descs[6]
+		dst := &countingStorage{storage: cas.NewMemory()}
+		opts = oras.CopyGraphOptions{}
+		var numMountFrom atomic.Int64
+		e := errors.New("mountFrom error")
+		opts.MountFrom = func(ctx context.Context, desc ocispec.Descriptor) ([]string, error) {
+			numMountFrom.Add(1)
+			return nil, e
+		}
+		if err := oras.CopyGraph(ctx, src, dst, root, opts); !errors.Is(err, e) {
+			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, e)
+		}
+
+		if got, expected := dst.numExists.Load(), int64(7); got != expected {
+			t.Errorf("count(Exists()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numFetch.Load(), int64(0); got != expected {
+			t.Errorf("count(Fetch()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numPush.Load(), int64(0); got != expected {
+			t.Errorf("count(Push()) = %d, want %d", got, expected)
+		}
+		if got, expected := numMountFrom.Load(), int64(4); got != expected {
+			t.Errorf("count(MountFrom()) = %d, want %d", got, expected)
+		}
+	})
+
+	t.Run("MountFrom OnMounted error", func(t *testing.T) {
+		root = descs[6]
+		dst := &countingStorage{storage: cas.NewMemory()}
+		var numMount atomic.Int64
+		dst.mount = func(ctx context.Context,
+			desc ocispec.Descriptor,
+			fromRepo string,
+			getContent func() (io.ReadCloser, error),
+		) error {
+			numMount.Add(1)
+			if expected := "source"; fromRepo != expected {
+				t.Fatalf("fromRepo = %v, want %v", fromRepo, expected)
+			}
+			rc, err := src.Fetch(ctx, desc)
+			if err != nil {
+				t.Fatalf("Failed to fetch content: %v", err)
+			}
+			defer rc.Close()
+			err = dst.storage.Push(ctx, desc, rc) // bypass the counters
+			if err != nil {
+				t.Fatalf("Failed to push content: %v", err)
+			}
+			return nil
+		}
+		opts = oras.CopyGraphOptions{}
+		var numPreCopy, numPostCopy, numOnMounted, numMountFrom atomic.Int64
+		opts.PreCopy = func(ctx context.Context, desc ocispec.Descriptor) error {
+			numPreCopy.Add(1)
+			return nil
+		}
+		opts.PostCopy = func(ctx context.Context, desc ocispec.Descriptor) error {
+			numPostCopy.Add(1)
+			return nil
+		}
+		e := errors.New("onMounted error")
+		opts.OnMounted = func(ctx context.Context, d ocispec.Descriptor) error {
+			numOnMounted.Add(1)
+			return e
+		}
+		opts.MountFrom = func(ctx context.Context, desc ocispec.Descriptor) ([]string, error) {
+			numMountFrom.Add(1)
+			return []string{"source"}, nil
+		}
+		if err := oras.CopyGraph(ctx, src, dst, root, opts); !errors.Is(err, e) {
+			t.Fatalf("CopyGraph() error = %v, wantErr %v", err, e)
+		}
+
+		if got, expected := dst.numExists.Load(), int64(7); got != expected {
+			t.Errorf("count(Exists()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numFetch.Load(), int64(0); got != expected {
+			t.Errorf("count(Fetch()) = %d, want %d", got, expected)
+		}
+		if got, expected := dst.numPush.Load(), int64(0); got != expected {
+			t.Errorf("count(Push()) = %d, want %d", got, expected)
+		}
+		if got, expected := numMount.Load(), int64(4); got != expected {
+			t.Errorf("count(Mount()) = %d, want %d", got, expected)
+		}
+		if got, expected := numOnMounted.Load(), int64(4); got != expected {
+			t.Errorf("count(OnMounted()) = %d, want %d", got, expected)
+		}
+		if got, expected := numMountFrom.Load(), int64(4); got != expected {
+			t.Errorf("count(MountFrom()) = %d, want %d", got, expected)
+		}
+		if got, expected := numPreCopy.Load(), int64(0); got != expected {
+			t.Errorf("count(PreCopy()) = %d, want %d", got, expected)
+		}
+		if got, expected := numPostCopy.Load(), int64(0); got != expected {
+			t.Errorf("count(PostCopy()) = %d, want %d", got, expected)
+		}
+	})
 }
 
 // countingStorage counts the calls to its content.Storage methods