diff --git a/builder/docker/artifact_import.go b/builder/docker/artifact_import.go
index c626a9df3..a53c0a52b 100644
--- a/builder/docker/artifact_import.go
+++ b/builder/docker/artifact_import.go
@@ -30,19 +30,22 @@ func (a *ImportArtifact) Id() string {
 }
 
 func (a *ImportArtifact) String() string {
-	tags := a.StateData["docker_tags"]
-	if tags == nil {
-		return fmt.Sprintf("Imported Docker image: %s", a.Id())
-	}
-	cast := tags.([]interface{})
-	names := []string{}
-	for _, name := range cast {
-		if n, ok := name.(string); ok {
-			names = append(names, n)
+	var tags []string
+	switch t := a.StateData["docker_tags"].(type) {
+	case []string:
+		tags = t
+	case []interface{}:
+		for _, name := range t {
+			if n, ok := name.(string); ok {
+				tags = append(tags, n)
+			}
 		}
 	}
-	return fmt.Sprintf("Imported Docker image: %s with tags %s",
-		a.Id(), strings.Join(names, " "))
+	if len(tags) > 0 {
+		return fmt.Sprintf("Imported Docker image: %s with tags %s",
+			a.Id(), strings.Join(tags, " "))
+	}
+	return fmt.Sprintf("Imported Docker image: %s", a.Id())
 }
 
 func (a *ImportArtifact) State(name string) interface{} {
diff --git a/packer/rpc/post_processor.go b/packer/rpc/post_processor.go
index 4b36f2dd4..00d492a0a 100644
--- a/packer/rpc/post_processor.go
+++ b/packer/rpc/post_processor.go
@@ -99,28 +99,42 @@ func (p *PostProcessorServer) PostProcess(streamId uint32, reply *PostProcessorP
 	if err != nil {
 		return NewBasicError(err)
 	}
-	defer client.Close()
 
 	if p.context == nil {
 		p.context, p.contextCancel = context.WithCancel(context.Background())
 	}
 
-	streamId = 0
-	artifactResult, keep, forceOverride, err := p.p.PostProcess(p.context, client.Ui(), client.Artifact())
-	if err == nil && artifactResult != nil {
-		streamId = p.mux.NextId()
-		server := newServerWithMux(p.mux, streamId)
-		server.RegisterArtifact(artifactResult)
-		go server.Serve()
-	}
-
+	artifact := client.Artifact()
+	artifactResult, keep, forceOverride, err := p.p.PostProcess(p.context, client.Ui(), artifact)
 	*reply = PostProcessorProcessResponse{
 		Err:           NewBasicError(err),
 		Keep:          keep,
 		ForceOverride: forceOverride,
-		StreamId:      streamId,
+		StreamId:      0,
+	}
+	if err != nil {
+		log.Printf("error: %v", err)
+		client.Close()
+		return nil
 	}
 
+	if artifactResult != artifact {
+		// Sometimes, the artifact returned by PostProcess is the artifact from
+		// client.Artifact() and in that case we don't want to close client;
+		// otherwise the outcome is sort of undetermined. See [GH-9995] for a
+		// good test file.
+		defer client.Close()
+	}
+
+	if artifactResult != nil {
+		streamId = p.mux.NextId()
+		reply.StreamId = streamId
+		server := newServerWithMux(p.mux, streamId)
+		if err := server.RegisterArtifact(artifactResult); err != nil {
+			return err
+		}
+		go server.Serve()
+	}
 	return nil
 }
 
diff --git a/post-processor/docker-push/post-processor.go b/post-processor/docker-push/post-processor.go
index 979ea2896..97ffb8627 100644
--- a/post-processor/docker-push/post-processor.go
+++ b/post-processor/docker-push/post-processor.go
@@ -5,7 +5,6 @@ package dockerpush
 import (
 	"context"
 	"fmt"
-
 	"github.com/hashicorp/hcl/v2/hcldec"
 	"github.com/hashicorp/packer/builder/docker"
 	"github.com/hashicorp/packer/common"
@@ -103,17 +102,21 @@ func (p *PostProcessor) PostProcess(ctx context.Context, ui packer.Ui, artifact
 		}()
 	}
 
-	names := []string{artifact.Id()}
-	tags := artifact.State("docker_tags")
-	if tags != nil {
-		cast := tags.([]interface{})
-		for _, name := range cast {
+	var tags []string
+	switch t := artifact.State("docker_tags").(type) {
+	case []string:
+		tags = t
+	case []interface{}:
+		for _, name := range t {
 			if n, ok := name.(string); ok {
-				names = append(names, n)
+				tags = append(tags, n)
 			}
 		}
 	}
 
+	names := []string{artifact.Id()}
+	names = append(names, tags...)
+
 	// Get the name.
 	for _, name := range names {
 		ui.Message("Pushing: " + name)