diff --git a/sources/diagram.cpp b/sources/diagram.cpp
index 2ea8bf045..71f79848f 100644
--- a/sources/diagram.cpp
+++ b/sources/diagram.cpp
@@ -1864,6 +1864,28 @@ void Diagram::changeZValue(QET::DepthOption option)
 		delete undo;
 }
 
+int Diagram::uniqueTerminalID() const
+{
+    for (int i=1; i < 10000; i++) {
+        bool found = false;
+        for (auto element: elements()) {
+            for (auto terminal: element->terminals()) {
+                if (terminal->ID() == i) {
+                    found = true;
+                    break;
+                }
+            }
+            if (found) {
+                break;
+            }
+        }
+
+        if (!found)
+            return i;
+    }
+    return -1;
+}
+
 /**
 	@brief Diagram::loadElmtFolioSeq
 	This class loads all folio sequential variables related
diff --git a/sources/diagram.h b/sources/diagram.h
index 5928747a5..a036f53a4 100644
--- a/sources/diagram.h
+++ b/sources/diagram.h
@@ -257,6 +257,13 @@ class Diagram : public QGraphicsScene
 					   NumerotationContext *nc);
 		void changeZValue(QET::DepthOption option);
 
+		/*!
+		 * \brief uniqueTerminalID
+		 * Determines a new unique Terminal ID
+		 * This is used only for legacy purpose
+		 */
+        int uniqueTerminalID() const;
+
 	public slots:
 		void adjustSceneRect ();
 		void titleChanged(const QString &);
diff --git a/sources/qetgraphicsitem/element.cpp b/sources/qetgraphicsitem/element.cpp
index 0f330a778..bc5b7dda9 100644
--- a/sources/qetgraphicsitem/element.cpp
+++ b/sources/qetgraphicsitem/element.cpp
@@ -944,8 +944,15 @@ QDomElement Element::toXml(
 		QDomElement terminal = t -> toXml(document);
 		if (t->ID() > 0) {
 			// for backward compatibility
+            // Terminal was loaded during loading an old project. So the terminal has a valid id
 			terminal.setAttribute("id", t->ID()); // for backward compatibility
-		}
+        } else if (t->uuid().isNull()) {
+          // for backward compatibility
+          // An old element with no uuid on the terminals was added to the project.
+          // give it an id
+          t->setID(t->diagram()->uniqueTerminalID());
+          terminal.setAttribute("id", t->ID());
+        }
 		xml_terminals.appendChild(terminal);
 	}
 	element.appendChild(xml_terminals);