API/Transitions.md

@@ -247,3 +247,18 @@ Should the request fail, an error message including a "hint" as to how the reque
 # Dereferencing /data/$module/$entity/$instance_id/transitions/$transition/deref
 
 NOT YET DOCUMENTED
+
+# Errors
+
+```json
+    "error": {
+      "involvedAttributes": [
+        null
+      ],
+      "entity": null,
+      "module": null,
+      "errorDescription": "unexpected_backend_error",
+      "errorType": "SYSTEM",
+      "errorID": 429
+    },
+```
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