diff --git a/dashboard_api_rev.py b/dashboard_api_rev.py
index 31c33d3..7ea9dc4 100644
--- a/dashboard_api_rev.py
+++ b/dashboard_api_rev.py
@@ -205,7 +205,10 @@ def ingest_health():
             else "stale" if any(r["freshness"] == "stale" for r in rows)
             else "ok"
         ) if rows else "unknown"
-        return JSONResponse({"overall": worst, "endpoints": rows})
+        # rows carry last_run_at (datetime) — jsonable_encoder (Decimal→float,
+        # datetime→ISO) before JSONResponse, else json.dumps raises TypeError
+        # and the whole feed 500s into the except below. (260702 fix.)
+        return JSONResponse(jsonable_encoder({"overall": worst, "endpoints": rows}))
     except Exception:
         log.exception("ingest-health failed")
         return JSONResponse(