diff --git a/server/http_config_metadata_handler.go b/server/http_config_metadata_handler.go
index a58887001..fe3ce2684 100644
--- a/server/http_config_metadata_handler.go
+++ b/server/http_config_metadata_handler.go
@@ -9,6 +9,16 @@ import (
 	"github.com/gorilla/mux"
 )
 
+var supportedLanguages = []string{"en", "de"}
+
+func getLang(r *http.Request) string {
+	lang := r.URL.Query().Get("lang")
+	if !slices.Contains(supportedLanguages, lang) {
+		lang = supportedLanguages[0]
+	}
+	return lang
+}
+
 // templatesHandler returns the list of templates by class
 func templatesHandler(w http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)
@@ -19,7 +29,7 @@ func templatesHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	lang := r.URL.Query().Get("lang")
+	lang := getLang(r)
 	templates.EncoderLanguage(lang)
 
 	if name := r.URL.Query().Get("name"); name != "" {
@@ -60,7 +70,7 @@ func productsHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	tmpl := templates.ByClass(class)
-	lang := r.URL.Query().Get("lang")
+	lang := getLang(r)
 	usage := r.URL.Query().Get("usage")
 
 	res := make(products, 0)