@@ -97,7 +97,7 @@ func (s *systemRouter) getDiskUsage(ctx context.Context, w http.ResponseWriter,

 		var err error

 		buildCache, err = s.builder.DiskUsage(ctx)

 		if err != nil {

-			return pkgerrors.Wrap(err, "error getting fscache build cache usage")

+			return pkgerrors.Wrap(err, "error getting build cache usage")

 		}

 		return nil

 	})

@@ -291,15 +291,14 @@ func (p *puller) Snapshot(ctx context.Context) (cache.ImmutableRef, error) {

 	}

 	if p.config != nil {

-		img, err := p.is.ImageStore.Get(image.ID(digest.Digest(p.config)))

-		if err != nil {

-			return nil, err

-		}

-		ref, err := p.is.CacheAccessor.GetFromSnapshotter(ctx, string(img.RootFS.ChainID()), cache.WithDescription(fmt.Sprintf("from local %s", p.ref)))

-		if err != nil {

-			return nil, err

+		img, err := p.is.ImageStore.Get(image.ID(digest.FromBytes(p.config)))

+		if err == nil {

+			ref, err := p.is.CacheAccessor.GetFromSnapshotter(ctx, string(img.RootFS.ChainID()), cache.WithDescription(fmt.Sprintf("from local %s", p.ref)))

+			if err != nil {

+				return nil, err

+			}

+			return ref, nil

 		}

-		return ref, nil

 	}

 	ongoing := newJobs(p.ref)

@@ -307,6 +307,9 @@ func (s *snapshotter) Remove(ctx context.Context, key string) error {

 	}

 	if l != nil {

+		s.mu.Lock()

+		delete(s.refs, key)

+		s.mu.Unlock()

 		_, err := s.opt.LayerStore.Release(l)

 		return err

 	}

@@ -109,6 +109,15 @@ func (b *Builder) Prune(ctx context.Context) (int64, error) {

 }

 func (b *Builder) Build(ctx context.Context, opt backend.BuildConfig) (*builder.Result, error) {

+	if buildID := opt.Options.BuildID; buildID != "" {

+		b.mu.Lock()

+		ctx, b.jobs[buildID] = context.WithCancel(ctx)

+		b.mu.Unlock()

+		defer func() {

+			delete(b.jobs, buildID)

+		}()

+	}

+

 	var out builder.Result

 	id := identity.NewID()

@@ -73,23 +73,26 @@ func (e *imageExporterInstance) Export(ctx context.Context, ref cache.ImmutableR

 	}

 	config := e.config

-	layersDone := oneOffProgress(ctx, "exporting layers")

+	var diffs []digest.Digest

+	if ref != nil {

+		layersDone := oneOffProgress(ctx, "exporting layers")

-	if err := ref.Finalize(ctx); err != nil {

-		return nil, err

-	}

+		if err := ref.Finalize(ctx); err != nil {

+			return nil, err

+		}

-	diffIDs, err := e.opt.Differ.EnsureLayer(ctx, ref.ID())

-	if err != nil {

-		return nil, err

-	}

+		diffIDs, err := e.opt.Differ.EnsureLayer(ctx, ref.ID())

+		if err != nil {

+			return nil, err

+		}

-	diffs := make([]digest.Digest, len(diffIDs))

-	for i := range diffIDs {

-		diffs[i] = digest.Digest(diffIDs[i])

-	}

+		diffs = make([]digest.Digest, len(diffIDs))

+		for i := range diffIDs {

+			diffs[i] = digest.Digest(diffIDs[i])

+		}

-	layersDone(nil)

+		layersDone(nil)

+	}

 	if len(config) == 0 {

 		var err error