diff --git a/frontend/dockerfile/dockerfile2llb/convert.go b/frontend/dockerfile/dockerfile2llb/convert.go
index 4bb9d8903b889..1482545d9d283 100644
--- a/frontend/dockerfile/dockerfile2llb/convert.go
+++ b/frontend/dockerfile/dockerfile2llb/convert.go
@@ -492,6 +492,8 @@ func toDispatchState(ctx context.Context, dt []byte, opt ConvertOpt) (*dispatchS
 		if !isReachable(target, d) || d.noinit {
 			continue
 		}
+		// mark as initialized, used to determine states that have not been dispatched yet
+		d.noinit = true
 
 		if d.base != nil {
 			d.state = d.base.state
@@ -651,6 +653,7 @@ func toCommand(ic instructions.Command, allDispatchStates *dispatchStates) (comm
 						deps:         make(map[*dispatchState]instructions.Command),
 						paths:        make(map[string]struct{}),
 						unregistered: true,
+						noinit:       true,
 					}
 				}
 			} else {
@@ -779,7 +782,11 @@ func dispatch(d *dispatchState, cmd command, opt dispatchOpt) error {
 	case *instructions.CopyCommand:
 		l := opt.buildContext
 		if len(cmd.sources) != 0 {
-			l = cmd.sources[0].state
+			src := cmd.sources[0]
+			if !src.noinit {
+				return errors.Errorf("cannot copy from stage %q, it needs to be defined before current stage %q", c.From, d.stageName)
+			}
+			l = src.state
 		}
 		err = dispatchCopy(d, copyConfig{
 			params:       c.SourcesAndDest,
diff --git a/frontend/dockerfile/dockerfile2llb/convert_runmount.go b/frontend/dockerfile/dockerfile2llb/convert_runmount.go
index 1f4597eb23af6..83c1b9dd64822 100644
--- a/frontend/dockerfile/dockerfile2llb/convert_runmount.go
+++ b/frontend/dockerfile/dockerfile2llb/convert_runmount.go
@@ -33,6 +33,7 @@ func detectRunMount(cmd *command, allDispatchStates *dispatchStates) bool {
 					deps:         make(map[*dispatchState]instructions.Command),
 					paths:        make(map[string]struct{}),
 					unregistered: true,
+					noinit:       true,
 				}
 			}
 			sources[i] = stn
@@ -65,12 +66,27 @@ func dispatchRunMounts(d *dispatchState, c *instructions.RunCommand, sources []*
 	mounts := instructions.GetMounts(c)
 
 	for i, mount := range mounts {
+		target := mount.Target
+		if !filepath.IsAbs(filepath.Clean(mount.Target)) {
+			dir, err := d.state.GetDir(context.TODO())
+			if err != nil {
+				return nil, err
+			}
+			target = filepath.Join("/", dir, mount.Target)
+		}
+		if target == "/" {
+			return nil, errors.Errorf("invalid mount target %q", target)
+		}
 		if mount.From == "" && mount.Type == instructions.MountTypeCache {
 			mount.From = emptyImageName
 		}
 		st := opt.buildContext
 		if mount.From != "" {
-			st = sources[i].state
+			src := sources[i]
+			st = src.state
+			if !src.noinit {
+				return nil, errors.Errorf("cannot mount from stage %q to %q, stage needs to be defined before current command", mount.From, target)
+			}
 		}
 		var mountOpts []llb.MountOption
 		if mount.Type == instructions.MountTypeTmpfs {
@@ -113,17 +129,7 @@ func dispatchRunMounts(d *dispatchState, c *instructions.RunCommand, sources []*
 			}
 			mountOpts = append(mountOpts, llb.AsPersistentCacheDir(opt.cacheIDNamespace+"/"+mount.CacheID, sharing))
 		}
-		target := mount.Target
-		if !filepath.IsAbs(filepath.Clean(mount.Target)) {
-			dir, err := d.state.GetDir(context.TODO())
-			if err != nil {
-				return nil, err
-			}
-			target = filepath.Join("/", dir, mount.Target)
-		}
-		if target == "/" {
-			return nil, errors.Errorf("invalid mount target %q", target)
-		}
+
 		if src := path.Join("/", mount.Source); src != "/" {
 			mountOpts = append(mountOpts, llb.SourcePath(src))
 		} else {
diff --git a/frontend/dockerfile/dockerfile_test.go b/frontend/dockerfile/dockerfile_test.go
index 7b3a0a225d347..16199e766c98b 100644
--- a/frontend/dockerfile/dockerfile_test.go
+++ b/frontend/dockerfile/dockerfile_test.go
@@ -156,6 +156,7 @@ var allTests = integration.TestFuncs(
 	testWorkdirUser,
 	testWorkdirExists,
 	testWorkdirCopyIgnoreRelative,
+	testOutOfOrderStage,
 	testCopyFollowAllSymlinks,
 	testDockerfileAddChownExpand,
 	testSourceDateEpochWithoutExporter,
@@ -953,6 +954,42 @@ RUN [ "$(stat -c "%U %G" /mydir)" == "user user" ]
 	require.NoError(t, err)
 }
 
+func testOutOfOrderStage(t *testing.T, sb integration.Sandbox) {
+	integration.SkipOnPlatform(t, "windows")
+	f := getFrontend(t, sb)
+
+	for _, src := range []string{"/", "/d2"} {
+		dockerfile := []byte(fmt.Sprintf(`
+FROM busybox AS target
+COPY --from=build %s /out
+
+FROM alpine AS build
+COPY /Dockerfile /d2
+
+FROM target
+`, src))
+
+		dir := integration.Tmpdir(
+			t,
+			fstest.CreateFile("Dockerfile", dockerfile, 0600),
+		)
+
+		c, err := client.New(sb.Context(), sb.Address())
+		require.NoError(t, err)
+		defer c.Close()
+
+		_, err = f.Solve(sb.Context(), c, client.SolveOpt{
+			LocalDirs: map[string]string{
+				dockerui.DefaultLocalNameDockerfile: dir,
+				dockerui.DefaultLocalNameContext:    dir,
+			},
+		}, nil)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "cannot copy from stage")
+		require.Contains(t, err.Error(), "needs to be defined before current stage")
+	}
+}
+
 func testWorkdirCopyIgnoreRelative(t *testing.T, sb integration.Sandbox) {
 	integration.SkipOnPlatform(t, "windows")
 	f := getFrontend(t, sb)