diff --git a/backend/src/routes/stellar.js b/backend/src/routes/stellar.js
index b3158d11..a4ded6ae 100644
--- a/backend/src/routes/stellar.js
+++ b/backend/src/routes/stellar.js
@@ -219,6 +219,9 @@ router.get('/exchange-rate/:from/:to', rules.assetCodeParams, validate,
     try {
       const { from, to } = req.params;
       const rate = await getRate(from, to);
+      if (rate === null) {
+        return res.status(503).json({ error: `Exchange rate unavailable for ${from}/${to}: no liquidity in orderbook` });
+      }
       res.json({ from, to, rate });
     } catch (error) {
       res.status(500).json({ error: error.message });