diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
index 529128b9a21..1fbb6ff2ed2 100644
--- a/core/io/resource_loader.cpp
+++ b/core/io/resource_loader.cpp
@@ -1113,11 +1113,10 @@ bool ResourceLoader::add_custom_resource_format_loader(String script_path) {
 	Ref<Script> s = res;
 	StringName ibt = s->get_instance_base_type();
 	bool valid_type = ClassDB::is_parent_class(ibt, "ResourceFormatLoader");
-	ERR_FAIL_COND_V_MSG(!valid_type, false, "Script does not inherit a CustomResourceLoader: " + script_path + ".");
+	ERR_FAIL_COND_V_MSG(!valid_type, false, vformat("Failed to add a custom resource loader, script '%s' does not inherit 'ResourceFormatLoader'.", script_path));
 
 	Object *obj = ClassDB::instantiate(ibt);
-
-	ERR_FAIL_NULL_V_MSG(obj, false, "Cannot instance script as custom resource loader, expected 'ResourceFormatLoader' inheritance, got: " + String(ibt) + ".");
+	ERR_FAIL_NULL_V_MSG(obj, false, vformat("Failed to add a custom resource loader, cannot instantiate '%s'.", ibt));
 
 	Ref<ResourceFormatLoader> crl = Object::cast_to<ResourceFormatLoader>(obj);
 	crl->set_script(s);
diff --git a/core/io/resource_saver.cpp b/core/io/resource_saver.cpp
index 564a54b913a..1c6c18b0151 100644
--- a/core/io/resource_saver.cpp
+++ b/core/io/resource_saver.cpp
@@ -237,11 +237,10 @@ bool ResourceSaver::add_custom_resource_format_saver(String script_path) {
 	Ref<Script> s = res;
 	StringName ibt = s->get_instance_base_type();
 	bool valid_type = ClassDB::is_parent_class(ibt, "ResourceFormatSaver");
-	ERR_FAIL_COND_V_MSG(!valid_type, false, "Script does not inherit a CustomResourceSaver: " + script_path + ".");
+	ERR_FAIL_COND_V_MSG(!valid_type, false, vformat("Failed to add a custom resource saver, script '%s' does not inherit 'ResourceFormatSaver'.", script_path));
 
 	Object *obj = ClassDB::instantiate(ibt);
-
-	ERR_FAIL_NULL_V_MSG(obj, false, "Cannot instance script as custom resource saver, expected 'ResourceFormatSaver' inheritance, got: " + String(ibt) + ".");
+	ERR_FAIL_NULL_V_MSG(obj, false, vformat("Failed to add a custom resource saver, cannot instantiate '%s'.", ibt));
 
 	Ref<ResourceFormatSaver> crl = Object::cast_to<ResourceFormatSaver>(obj);
 	crl->set_script(s);
diff --git a/editor/editor_autoload_settings.cpp b/editor/editor_autoload_settings.cpp
index be05bfea68b..204b7172963 100644
--- a/editor/editor_autoload_settings.cpp
+++ b/editor/editor_autoload_settings.cpp
@@ -407,31 +407,30 @@ Node *EditorAutoloadSettings::_create_autoload(const String &p_path) {
 		scn.instantiate();
 		scn->set_path(p_path);
 		scn->reload_from_file();
-		ERR_FAIL_COND_V_MSG(!scn.is_valid(), nullptr, vformat("Can't autoload: %s.", p_path));
+		ERR_FAIL_COND_V_MSG(!scn.is_valid(), nullptr, vformat("Failed to create an autoload, can't load from path: %s.", p_path));
 
 		if (scn.is_valid()) {
 			n = scn->instantiate();
 		}
 	} else {
 		Ref<Resource> res = ResourceLoader::load(p_path);
-		ERR_FAIL_COND_V_MSG(res.is_null(), nullptr, vformat("Can't autoload: %s.", p_path));
+		ERR_FAIL_COND_V_MSG(res.is_null(), nullptr, vformat("Failed to create an autoload, can't load from path: %s.", p_path));
 
 		Ref<Script> scr = res;
 		if (scr.is_valid()) {
 			StringName ibt = scr->get_instance_base_type();
 			bool valid_type = ClassDB::is_parent_class(ibt, "Node");
-			ERR_FAIL_COND_V_MSG(!valid_type, nullptr, vformat("Script does not inherit from Node: %s.", p_path));
+			ERR_FAIL_COND_V_MSG(!valid_type, nullptr, vformat("Failed to create an autoload, script '%s' does not inherit from 'Node'.", p_path));
 
 			Object *obj = ClassDB::instantiate(ibt);
-
-			ERR_FAIL_NULL_V_MSG(obj, nullptr, vformat("Cannot instance script for Autoload, expected 'Node' inheritance, got: %s.", ibt));
+			ERR_FAIL_NULL_V_MSG(obj, nullptr, vformat("Failed to create an autoload, cannot instantiate '%s'.", ibt));
 
 			n = Object::cast_to<Node>(obj);
 			n->set_script(scr);
 		}
 	}
 
-	ERR_FAIL_NULL_V_MSG(n, nullptr, vformat("Path in Autoload not a node or script: %s.", p_path));
+	ERR_FAIL_NULL_V_MSG(n, nullptr, vformat("Failed to create an autoload, path is not pointing to a scene or a script: %s.", p_path));
 
 	return n;
 }
diff --git a/editor/editor_node.cpp b/editor/editor_node.cpp
index b2a65063a76..535fb5f3974 100644
--- a/editor/editor_node.cpp
+++ b/editor/editor_node.cpp
@@ -3459,13 +3459,13 @@ void EditorNode::set_addon_plugin_enabled(const String &p_addon, bool p_enabled,
 		}
 
 		// Plugin init scripts must inherit from EditorPlugin and be tools.
-		if (String(scr->get_instance_base_type()) != "EditorPlugin") {
-			show_warning(vformat(TTR("Unable to load addon script from path: '%s' Base type is not EditorPlugin."), script_path));
+		if (!ClassDB::is_parent_class(scr->get_instance_base_type(), "EditorPlugin")) {
+			show_warning(vformat(TTR("Unable to load addon script from path: '%s'. Base type is not 'EditorPlugin'."), script_path));
 			return;
 		}
 
 		if (!scr->is_tool()) {
-			show_warning(vformat(TTR("Unable to load addon script from path: '%s' Script is not in tool mode."), script_path));
+			show_warning(vformat(TTR("Unable to load addon script from path: '%s'. Script is not in tool mode."), script_path));
 			return;
 		}
 	}
diff --git a/editor/plugins/script_text_editor.cpp b/editor/plugins/script_text_editor.cpp
index 9ed997dca75..04eda502d20 100644
--- a/editor/plugins/script_text_editor.cpp
+++ b/editor/plugins/script_text_editor.cpp
@@ -1650,7 +1650,7 @@ void ScriptTextEditor::reload(bool p_soft) {
 		return;
 	}
 	scr->set_source_code(te->get_text());
-	bool soft = p_soft || scr->get_instance_base_type() == "EditorPlugin"; // Always soft-reload editor plugins.
+	bool soft = p_soft || ClassDB::is_parent_class(scr->get_instance_base_type(), "EditorPlugin"); // Always soft-reload editor plugins.
 
 	scr->get_language()->reload_tool_script(scr, soft);
 }
diff --git a/main/main.cpp b/main/main.cpp
index 281ef9a0d69..f36526d433e 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -3192,31 +3192,30 @@ bool Main::start() {
 						scn.instantiate();
 						scn->set_path(info.path);
 						scn->reload_from_file();
-						ERR_CONTINUE_MSG(!scn.is_valid(), vformat("Can't autoload: %s.", info.path));
+						ERR_CONTINUE_MSG(!scn.is_valid(), vformat("Failed to instantiate an autoload, can't load from path: %s.", info.path));
 
 						if (scn.is_valid()) {
 							n = scn->instantiate();
 						}
 					} else {
 						Ref<Resource> res = ResourceLoader::load(info.path);
-						ERR_CONTINUE_MSG(res.is_null(), vformat("Can't autoload: %s.", info.path));
+						ERR_CONTINUE_MSG(res.is_null(), vformat("Failed to instantiate an autoload, can't load from path: %s.", info.path));
 
 						Ref<Script> script_res = res;
 						if (script_res.is_valid()) {
 							StringName ibt = script_res->get_instance_base_type();
 							bool valid_type = ClassDB::is_parent_class(ibt, "Node");
-							ERR_CONTINUE_MSG(!valid_type, vformat("Script does not inherit from Node: %s.", info.path));
+							ERR_CONTINUE_MSG(!valid_type, vformat("Failed to instantiate an autoload, script '%s' does not inherit from 'Node'.", info.path));
 
 							Object *obj = ClassDB::instantiate(ibt);
-
-							ERR_CONTINUE_MSG(!obj, vformat("Cannot instance script for autoload, expected 'Node' inheritance, got: %s."));
+							ERR_CONTINUE_MSG(!obj, vformat("Failed to instantiate an autoload, cannot instantiate '%s'.", ibt));
 
 							n = Object::cast_to<Node>(obj);
 							n->set_script(script_res);
 						}
 					}
 
-					ERR_CONTINUE_MSG(!n, vformat("Path in autoload not a node or script: %s.", info.path));
+					ERR_CONTINUE_MSG(!n, vformat("Failed to instantiate an autoload, path is not pointing to a scene or a script: %s.", info.path));
 					n->set_name(info.name);
 
 					//defer so references are all valid on _ready()
diff --git a/modules/gdscript/tests/gdscript_test_runner.cpp b/modules/gdscript/tests/gdscript_test_runner.cpp
index f91dc83f2cc..361ca276bb2 100644
--- a/modules/gdscript/tests/gdscript_test_runner.cpp
+++ b/modules/gdscript/tests/gdscript_test_runner.cpp
@@ -78,31 +78,30 @@ void init_autoloads() {
 			scn.instantiate();
 			scn->set_path(info.path);
 			scn->reload_from_file();
-			ERR_CONTINUE_MSG(!scn.is_valid(), vformat("Can't autoload: %s.", info.path));
+			ERR_CONTINUE_MSG(!scn.is_valid(), vformat("Failed to instantiate an autoload, can't load from path: %s.", info.path));
 
 			if (scn.is_valid()) {
 				n = scn->instantiate();
 			}
 		} else {
 			Ref<Resource> res = ResourceLoader::load(info.path);
-			ERR_CONTINUE_MSG(res.is_null(), vformat("Can't autoload: %s.", info.path));
+			ERR_CONTINUE_MSG(res.is_null(), vformat("Failed to instantiate an autoload, can't load from path: %s.", info.path));
 
 			Ref<Script> scr = res;
 			if (scr.is_valid()) {
 				StringName ibt = scr->get_instance_base_type();
 				bool valid_type = ClassDB::is_parent_class(ibt, "Node");
-				ERR_CONTINUE_MSG(!valid_type, vformat("Script does not inherit from Node: %s.", info.path));
+				ERR_CONTINUE_MSG(!valid_type, vformat("Failed to instantiate an autoload, script '%s' does not inherit from 'Node'.", info.path));
 
 				Object *obj = ClassDB::instantiate(ibt);
-
-				ERR_CONTINUE_MSG(!obj, vformat("Cannot instance script for Autoload, expected 'Node' inheritance, got: %s.", ibt));
+				ERR_CONTINUE_MSG(!obj, vformat("Failed to instantiate an autoload, cannot instantiate '%s'.", ibt));
 
 				n = Object::cast_to<Node>(obj);
 				n->set_script(scr);
 			}
 		}
 
-		ERR_CONTINUE_MSG(!n, vformat("Path in autoload not a node or script: %s.", info.path));
+		ERR_CONTINUE_MSG(!n, vformat("Failed to instantiate an autoload, path is not pointing to a scene or a script: %s.", info.path));
 		n->set_name(info.name);
 
 		for (int i = 0; i < ScriptServer::get_language_count(); i++) {