diff --git a/builder/azure/arm/config.go b/builder/azure/arm/config.go
index 10f3a47f7..799ae51f2 100644
--- a/builder/azure/arm/config.go
+++ b/builder/azure/arm/config.go
@@ -580,6 +580,7 @@ func (c *Config) createCertificate() (string, error) {
 func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	c.ctx.Funcs = azcommon.TemplateFuncs
 	err := config.Decode(c, &config.DecodeOpts{
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 	}, raws...)
diff --git a/builder/azure/dtl/config.go b/builder/azure/dtl/config.go
index 5009a5bab..d46cd82dc 100644
--- a/builder/azure/dtl/config.go
+++ b/builder/azure/dtl/config.go
@@ -389,6 +389,7 @@ func newConfig(raws ...interface{}) (*Config, []string, error) {
 	var c Config
 	c.ctx.Funcs = TemplateFuncs
 	err := config.Decode(&c, &config.DecodeOpts{
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 	}, raws...)
diff --git a/builder/docker/config.go b/builder/docker/config.go
index d04ce88f9..aa0b785e4 100644
--- a/builder/docker/config.go
+++ b/builder/docker/config.go
@@ -127,6 +127,7 @@ func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	var md mapstructure.Metadata
 	err := config.Decode(c, &config.DecodeOpts{
 		Metadata:           &md,
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/builder/googlecompute/config.go b/builder/googlecompute/config.go
index f10caaf4f..aea8e36a1 100644
--- a/builder/googlecompute/config.go
+++ b/builder/googlecompute/config.go
@@ -291,6 +291,7 @@ type Config struct {
 func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	c.ctx.Funcs = TemplateFuncs
 	err := config.Decode(c, &config.DecodeOpts{
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/builder/parallels/pvm/config.go b/builder/parallels/pvm/config.go
index 4f88ee193..bd9b421f6 100644
--- a/builder/parallels/pvm/config.go
+++ b/builder/parallels/pvm/config.go
@@ -51,6 +51,7 @@ type Config struct {
 
 func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	err := config.Decode(c, &config.DecodeOpts{
+		PluginType:         parallelscommon.BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/builder/qemu/config.go b/builder/qemu/config.go
index 081087ecf..1af05df37 100644
--- a/builder/qemu/config.go
+++ b/builder/qemu/config.go
@@ -394,6 +394,7 @@ type Config struct {
 
 func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	err := config.Decode(c, &config.DecodeOpts{
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/builder/scaleway/config.go b/builder/scaleway/config.go
index 6844cffab..c88e4fea5 100644
--- a/builder/scaleway/config.go
+++ b/builder/scaleway/config.go
@@ -99,6 +99,7 @@ func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 	var md mapstructure.Metadata
 	err := config.Decode(c, &config.DecodeOpts{
 		Metadata:           &md,
+		PluginType:         BuilderId,
 		Interpolate:        true,
 		InterpolateContext: &c.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/go.mod b/go.mod
index 3d2c7049b..e67ef5261 100644
--- a/go.mod
+++ b/go.mod
@@ -93,7 +93,6 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/go-testing-interface v1.0.3 // indirect
 	github.com/mitchellh/go-vnc v0.0.0-20150629162542-723ed9867aed
-	github.com/mitchellh/gox v1.0.1 // indirect
 	github.com/mitchellh/iochan v1.0.0
 	github.com/mitchellh/mapstructure v1.2.3
 	github.com/mitchellh/panicwrap v1.0.0
diff --git a/go.sum b/go.sum
index b92b448d9..1c0a21f59 100644
--- a/go.sum
+++ b/go.sum
@@ -377,7 +377,6 @@ github.com/hashicorp/go-uuid v1.0.1 h1:fv1ep09latC32wFoVwnqcnKJGnMSdBanPczbHAYm1
 github.com/hashicorp/go-uuid v1.0.1/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
 github.com/hashicorp/go-uuid v1.0.2 h1:cfejS+Tpcp13yd5nYHWDI6qVCny6wyX2Mt5SGur2IGE=
 github.com/hashicorp/go-uuid v1.0.2/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
-github.com/hashicorp/go-version v1.0.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/hashicorp/go-version v1.1.0 h1:bPIoEKD27tNdebFGGxxYwcL4nepeY4j1QP23PFRGzg0=
 github.com/hashicorp/go-version v1.1.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/hashicorp/go-version v1.2.0 h1:3vNe/fWF5CBgRIguda1meWhsZHy3m8gCJ5wx+dIzX/E=
@@ -512,8 +511,6 @@ github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7/go.mod h1:ZX
 github.com/mitchellh/go-wordwrap v1.0.0 h1:6GlHJ/LTGMrIJbwgdqdl2eEH8o+Exx/0m8ir9Gns0u4=
 github.com/mitchellh/go-wordwrap v1.0.0/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
 github.com/mitchellh/gox v0.4.0/go.mod h1:Sd9lOJ0+aimLBi73mGofS1ycjY8lL3uZM3JPS42BGNg=
-github.com/mitchellh/gox v1.0.1 h1:x0jD3dcHk9a9xPSDN6YEL4xL6Qz0dvNYm8yZqui5chI=
-github.com/mitchellh/gox v1.0.1/go.mod h1:ED6BioOGXMswlXa2zxfh/xdd5QhwYliBFn9V18Ap4z4=
 github.com/mitchellh/iochan v1.0.0 h1:C+X3KsSTLFVBr/tK1eYN/vs4rJcvsiLU338UhYPJWeY=
 github.com/mitchellh/iochan v1.0.0/go.mod h1:JwYml1nuB7xOzsp52dPpHFffvOCDupsG0QubkSMEySY=
 github.com/mitchellh/mapstructure v0.0.0-20160808181253-ca63d7c062ee/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
diff --git a/helper/config/decode.go b/helper/config/decode.go
index 6a4065ef5..e351d20d0 100644
--- a/helper/config/decode.go
+++ b/helper/config/decode.go
@@ -156,56 +156,57 @@ func Decode(target interface{}, config *DecodeOpts, raws ...interface{}) error {
 		if err := decoder.Decode(raw); err != nil {
 			return err
 		}
-		// If we have unused keys, it is an error
-		if len(md.Unused) > 0 {
-			var err error
-			sort.Strings(md.Unused)
-			for _, unused := range md.Unused {
-				if unused == "type" || strings.HasPrefix(unused, "packer_") {
-					continue
-				}
+	}
 
-				// Check for whether the key is handled in a packer fix
-				// call.
-				fixable := false
-
-				// check whether the deprecation option can be fixed using packer fix.
-				if config.PluginType != "" {
-					for k, deprecatedOptions := range DeprecatedOptions {
-						// the deprecated options keys are globbable, for
-						// example "amazon*" for all amazon builders, or * for
-						// all builders
-						if glob.Glob(k, config.PluginType) {
-							for _, deprecatedOption := range deprecatedOptions {
-								if unused == deprecatedOption {
-									fixable = true
-									break
-								}
+	// If we have unused keys, it is an error
+	if len(md.Unused) > 0 {
+		var err error
+		sort.Strings(md.Unused)
+		for _, unused := range md.Unused {
+			if unused == "type" || strings.HasPrefix(unused, "packer_") {
+				continue
+			}
+
+			// Check for whether the key is handled in a packer fix
+			// call.
+			fixable := false
+
+			// check whether the deprecation option can be fixed using packer fix.
+			if config.PluginType != "" {
+				for k, deprecatedOptions := range DeprecatedOptions {
+					// the deprecated options keys are globbable, for
+					// example "amazon*" for all amazon builders, or * for
+					// all builders
+					if glob.Glob(k, config.PluginType) {
+						for _, deprecatedOption := range deprecatedOptions {
+							if unused == deprecatedOption {
+								fixable = true
+								break
 							}
 						}
-						if fixable == true {
-							break
-						}
+					}
+					if fixable == true {
+						break
 					}
 				}
+			}
 
-				unusedErr := fmt.Errorf("unknown configuration key: '%q'",
-					unused)
-
-				if fixable {
-					unusedErr = fmt.Errorf("Deprecated configuration key: '%s'."+
-						" Please call `packer fix` against your template to "+
-						"update your template to be compatible with the current "+
-						"version of Packer. Visit "+
-						"https://www.packer.io/docs/commands/fix/ for more detail.",
-						unused)
-				}
+			unusedErr := fmt.Errorf("unknown configuration key: '%q'",
+				unused)
 
-				err = multierror.Append(err, unusedErr)
-			}
-			if err != nil {
-				return err
+			if fixable {
+				unusedErr = fmt.Errorf("Deprecated configuration key: '%s'."+
+					" Please call `packer fix` against your template to "+
+					"update your template to be compatible with the current "+
+					"version of Packer. Visit "+
+					"https://www.packer.io/docs/commands/fix/ for more detail.",
+					unused)
 			}
+
+			err = multierror.Append(err, unusedErr)
+		}
+		if err != nil {
+			return err
 		}
 	}
 
diff --git a/post-processor/manifest/post-processor.go b/post-processor/manifest/post-processor.go
index a11f308a1..c723d17fd 100644
--- a/post-processor/manifest/post-processor.go
+++ b/post-processor/manifest/post-processor.go
@@ -51,7 +51,7 @@ func (p *PostProcessor) ConfigSpec() hcldec.ObjectSpec { return p.config.FlatMap
 
 func (p *PostProcessor) Configure(raws ...interface{}) error {
 	err := config.Decode(&p.config, &config.DecodeOpts{
-		PluginType:         "manifest",
+		PluginType:         "packer.post-processor.manifest",
 		Interpolate:        true,
 		InterpolateContext: &p.config.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
diff --git a/post-processor/ucloud-import/post-processor.go b/post-processor/ucloud-import/post-processor.go
index 817b54fa6..276ab907a 100644
--- a/post-processor/ucloud-import/post-processor.go
+++ b/post-processor/ucloud-import/post-processor.go
@@ -83,6 +83,8 @@ func (p *PostProcessor) ConfigSpec() hcldec.ObjectSpec { return p.config.FlatMap
 
 func (p *PostProcessor) Configure(raws ...interface{}) error {
 	err := config.Decode(&p.config, &config.DecodeOpts{
+		PluginType:         BuilderId,
+		Interpolate:        true,
 		InterpolateContext: &p.config.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
 			Exclude: []string{