diff --git a/hcl2template/plugin.go b/hcl2template/plugin.go
index 15358573d..6a66aa610 100644
--- a/hcl2template/plugin.go
+++ b/hcl2template/plugin.go
@@ -55,6 +55,17 @@ func (cfg *PackerConfig) PluginRequirements() (plugingetter.Requirements, hcl.Di
 }
 
 func (cfg *PackerConfig) DetectPluginBinaries() hcl.Diagnostics {
+	// Do first pass to discover all the installed plugins
+	err := cfg.parser.PluginConfig.Discover()
+	if err != nil {
+		return (hcl.Diagnostics{}).Append(&hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Failed to discover installed plugins",
+			Detail:   err.Error(),
+		})
+	}
+
+	// Then we can apply any constraint from the template, if any
 	opts := plugingetter.ListInstallationsOptions{
 		PluginDirectory: cfg.parser.PluginConfig.PluginDirectory,
 		BinaryInstallationOptions: plugingetter.BinaryInstallationOptions{
diff --git a/main.go b/main.go
index bb1d741d6..553c173f4 100644
--- a/main.go
+++ b/main.go
@@ -339,9 +339,10 @@ func loadConfig() (*config, error) {
 		PluginMinPort:   10000,
 		PluginMaxPort:   25000,
 		PluginDirectory: pluginDir,
-	}
-	if err := config.Plugins.Discover(); err != nil {
-		return nil, err
+		Builders:        packer.MapOfBuilder{},
+		Provisioners:    packer.MapOfProvisioner{},
+		PostProcessors:  packer.MapOfPostProcessor{},
+		DataSources:     packer.MapOfDatasource{},
 	}
 
 	// Finally, try to use an internal plugin. Note that this will not override
diff --git a/packer/core.go b/packer/core.go
index 7a56dc06c..0f3ea9c9c 100644
--- a/packer/core.go
+++ b/packer/core.go
@@ -136,7 +136,18 @@ func NewCore(c *CoreConfig) *Core {
 // DetectPluginBinaries is used to load required plugins from the template,
 // since it is unsupported in JSON, this is essentially a no-op.
 func (c *Core) DetectPluginBinaries() hcl.Diagnostics {
-	return nil
+	var diags hcl.Diagnostics
+
+	err := c.components.PluginConfig.Discover()
+	if err != nil {
+		diags = diags.Append(&hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Failed to discover installed plugins",
+			Detail:   err.Error(),
+		})
+	}
+
+	return diags
 }
 
 func (c *Core) Initialize(_ InitializeOptions) hcl.Diagnostics {