diff --git a/builder/amazonebs/builder.go b/builder/amazonebs/builder.go
index 47f3a36aa..9e431faa2 100644
--- a/builder/amazonebs/builder.go
+++ b/builder/amazonebs/builder.go
@@ -100,21 +100,7 @@ func (b *Builder) Prepare(raw interface{}) error {
 	return nil
 }
 
-func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer.Artifact {
-	// Basic sanity checks. These are panics now because the Prepare
-	// method should verify these exist and such.
-	if b.config.AccessKey == "" {
-		panic("access key not filled in")
-	}
-
-	if b.config.SecretKey == "" {
-		panic("secret key not filled in")
-	}
-
-	if b.config.Region == "" {
-		panic("region not filled in")
-	}
-
+func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
 	region, ok := aws.Regions[b.config.Region]
 	if !ok {
 		panic("region not found")
@@ -147,11 +133,11 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer
 
 	// If there are no AMIs, then jsut return
 	if _, ok := state["amis"]; !ok {
-		return nil
+		return nil, nil
 	}
 
 	// Build the artifact and return it
-	return &artifact{state["amis"].(map[string]string)}
+	return &artifact{state["amis"].(map[string]string)}, nil
 }
 
 func (b *Builder) Cancel() {
diff --git a/builder/virtualbox/builder.go b/builder/virtualbox/builder.go
index 725d6d94f..b73cf6695 100644
--- a/builder/virtualbox/builder.go
+++ b/builder/virtualbox/builder.go
@@ -169,7 +169,7 @@ func (b *Builder) Prepare(raw interface{}) error {
 	return nil
 }
 
-func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer.Artifact {
+func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
 	steps := []multistep.Step{
 		new(stepDownloadISO),
 		new(stepPrepareOutputDir),
@@ -197,7 +197,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer
 	b.runner = &multistep.BasicRunner{Steps: steps}
 	b.runner.Run(state)
 
-	return nil
+	return nil, nil
 }
 
 func (b *Builder) Cancel() {
diff --git a/builder/vmware/builder.go b/builder/vmware/builder.go
index 5a824bd43..b502083df 100644
--- a/builder/vmware/builder.go
+++ b/builder/vmware/builder.go
@@ -184,7 +184,7 @@ func (b *Builder) Prepare(raw interface{}) error {
 	return nil
 }
 
-func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer.Artifact {
+func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
 	// Seed the random number generator
 	rand.Seed(time.Now().UTC().UnixNano())
 
@@ -216,11 +216,11 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer
 
 	// If we were interrupted or cancelled, then just exit.
 	if _, ok := state[multistep.StateCancelled]; ok {
-		return nil
+		return nil, nil
 	}
 
 	if _, ok := state[multistep.StateHalted]; ok {
-		return nil
+		return nil, nil
 	}
 
 	// Compile the artifact list
@@ -231,11 +231,10 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer
 	}
 
 	if err := filepath.Walk(b.config.OutputDir, visit); err != nil {
-		ui.Error(fmt.Sprintf("Error collecting result files: %s", err))
-		return nil
+		return nil, err
 	}
 
-	return &Artifact{b.config.OutputDir, files}
+	return &Artifact{b.config.OutputDir, files}, nil
 }
 
 func (b *Builder) Cancel() {
diff --git a/command/build/command.go b/command/build/command.go
index ba15b1cd3..de5c6d3d5 100644
--- a/command/build/command.go
+++ b/command/build/command.go
@@ -139,10 +139,16 @@ func (c Command) Run(env packer.Environment, args []string) int {
 		go func(b packer.Build) {
 			defer wg.Done()
 
+			var err error
 			log.Printf("Starting build run: %s", b.Name())
 			ui := buildUis[b.Name()]
-			artifacts[b.Name()] = b.Run(ui, env.Cache())
-			ui.Say("Build finished.")
+			artifacts[b.Name()], err = b.Run(ui, env.Cache())
+
+			if err != nil {
+				ui.Error(fmt.Sprintf("Build errored: %s", err))
+			} else {
+				ui.Say("Build finished.")
+			}
 		}(b)
 	}
 
diff --git a/packer/plugin/builder.go b/packer/plugin/builder.go
index cb37b5bc2..18a4061c2 100644
--- a/packer/plugin/builder.go
+++ b/packer/plugin/builder.go
@@ -19,7 +19,7 @@ func (b *cmdBuilder) Prepare(config interface{}) error {
 	return b.builder.Prepare(config)
 }
 
-func (b *cmdBuilder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) packer.Artifact {
+func (b *cmdBuilder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
 	defer func() {
 		r := recover()
 		b.checkExit(r, nil)
diff --git a/packer/plugin/builder_test.go b/packer/plugin/builder_test.go
index bb8e7b00b..ab24a13f8 100644
--- a/packer/plugin/builder_test.go
+++ b/packer/plugin/builder_test.go
@@ -12,8 +12,8 @@ func (helperBuilder) Prepare(interface{}) error {
 	return nil
 }
 
-func (helperBuilder) Run(packer.Ui, packer.Hook, packer.Cache) packer.Artifact {
-	return nil
+func (helperBuilder) Run(packer.Ui, packer.Hook, packer.Cache) (packer.Artifact, error) {
+	return nil, nil
 }
 
 func (helperBuilder) Cancel() {}