diff --git a/interfaces/iplugin.h b/interfaces/iplugin.h
--- a/interfaces/iplugin.h
+++ b/interfaces/iplugin.h
@@ -75,7 +75,7 @@
  * X-KDevelop-Category=
  * X-KDevelop-Mode=GUI
  * X-KDevelop-LoadMode=
- * X-KDevelop-Language=
+ * X-KDevelop-Languages=
  * X-KDevelop-SupportedMimeTypes=
  * X-KDevelop-Interfaces=
  * X-KDevelop-IOptional=
@@ -110,7 +110,7 @@
  * in which case a plugin of the given name is required which implements the interface.
  * - <i>X-KDevelop-IOptional</i> is a list of extension interfaces that this
  * plugin will use if they are available (optional);
- * - <i>X-KDevelop-Language</i> is the name of the language the plugin provides 
+ * - <i>X-KDevelop-Languages</i> is a list of the names of the languages the plugin provides
  *   support for (optional);
  * - <i>X-KDevelop-SupportedMimeTypes</i> is a list of mimetypes that the 
  *   language-parser in this plugin supports (optional);
diff --git a/interfaces/kdevelopplugin.desktop b/interfaces/kdevelopplugin.desktop
--- a/interfaces/kdevelopplugin.desktop
+++ b/interfaces/kdevelopplugin.desktop
@@ -83,9 +83,10 @@
 [PropertyDef::X-KDevelop-SupportedMimeTypes]
 Type=QStringList
 
-# optional, language supported by a language plugin
-[PropertyDef::X-KDevelop-Language]
-Type=QString
+# optional, languages supported by a language plugin
+# Example language names: "C", "C++", "Objective-C", "CMake"
+[PropertyDef::X-KDevelop-Languages]
+Type=QStringList
 
 # optional, defines whether the plugin can be disabled
 # by the user. Possible values are "AlwaysOn" and "UserSelectable".
diff --git a/language/codegen/sourcefiletemplate.h b/language/codegen/sourcefiletemplate.h
--- a/language/codegen/sourcefiletemplate.h
+++ b/language/codegen/sourcefiletemplate.h
@@ -51,8 +51,8 @@
  * with forward slashes. The top-level category is usually the language followed by the framework.
  * @li @c Type An optional type, which then adds some more default wizard pages and configuration.
  *             Currently supported are @c Class and @c Test.
- * @li @c Language The @c X-KDevelop-Language id of a language plugin which is then asked for a custom
- *                 createClassHelper.
+ * @li @c Language The @c X-KDevelop-Languages compatible id of a language plugin which is then asked
+ *                 for a custom @ref ICreateClassHelper object.
  * @li @c Files - List of files generated by this template. These are not actual file names, but names
  * of config groups describing those files.
  * @li @c OptionsFile (optional) - If the template uses custom configuration options, specify a path to
@@ -280,7 +280,7 @@
     QString type() const;
 
     /**
-     * aA optional @c X-KDevelop-Language by which a language plugin for this template can be found.
+     * An optional @c X-KDevelop-Languages compatible id by which a language plugin for this template can be found.
      */
     QString languageName() const;
 
diff --git a/plugins/patchreview/kdevpatchreview.json b/plugins/patchreview/kdevpatchreview.json
--- a/plugins/patchreview/kdevpatchreview.json
+++ b/plugins/patchreview/kdevpatchreview.json
@@ -72,7 +72,7 @@
         "org.kdevelop.IPatchReview", 
         "ILanguageSupport"
     ], 
-    "X-KDevelop-Language": "Diff", 
+    "X-KDevelop-Languages": ["Diff"], 
     "X-KDevelop-Mode": "GUI", 
     "X-KDevelop-SupportedMimeTypes": [
         "text/x-diff", 
diff --git a/shell/languagecontroller.cpp b/shell/languagecontroller.cpp
--- a/shell/languagecontroller.cpp
+++ b/shell/languagecontroller.cpp
@@ -211,9 +211,27 @@
     if(d->languages.contains(name))
         return d->languages[name];
 
-    QVariantMap constraints;
-    constraints.insert(QStringLiteral("X-KDevelop-Language"), name);
-    QList<IPlugin*> supports = Core::self()->pluginController()->allPluginsForExtension(KEY_ILanguageSupport(), constraints);
+    // temporary support for deprecated-in-5.1 "X-KDevelop-Language" as fallback
+    // remove in later version
+    const QString keys[2] = {
+        QStringLiteral("X-KDevelop-Languages"),
+        QStringLiteral("X-KDevelop-Language")
+    };
+    QList<IPlugin*> supports;
+    for (const auto& key : keys) {
+        QVariantMap constraints;
+        constraints.insert(key, name);
+        supports = Core::self()->pluginController()->allPluginsForExtension(KEY_ILanguageSupport(), constraints);
+        if (key == keys[1]) {
+            for (auto support : supports) {
+                qWarning() << "Plugin" << Core::self()->pluginController()->pluginInfo(support).name() << " has deprecated (since 5.1) metadata key \"X-KDevelop-Language\", needs porting to: \"X-KDevelop-Languages\": ["<<name<<"]'";
+            }
+        }
+        if (!supports.isEmpty()) {
+            break;
+        }
+    }
+
     if(!supports.isEmpty()) {
         ILanguageSupport *languageSupport = supports[0]->extension<ILanguageSupport>();
         if(languageSupport) {