a special error for when payments fail.

lnbits/core/services.py

@@ -29,6 +29,10 @@ from .crud import (
 )
 
 
+class PaymentFailure(Exception):
+    pass
+
+
 async def create_invoice(
     *,
     wallet_id: str,
@@ -162,8 +166,9 @@ async def pay_invoice(
                 )
                 await delete_payment(temp_id, conn=conn)
             else:
-                raise Exception(
-                    payment.error_message or "Failed to pay_invoice on backend."
+                raise PaymentFailure(
+                    payment.error_message
+                    or "Payment failed, but backend didn't give us an error message."
                 )
 
         return invoice.payment_hash

lnbits/core/views/api.py

@@ -12,7 +12,7 @@ from lnbits import bolt11
 from lnbits.decorators import api_check_wallet_key, api_validate_post_request
 
 from .. import core_app, db
-from ..services import create_invoice, pay_invoice, perform_lnurlauth
+from ..services import PaymentFailure, create_invoice, pay_invoice, perform_lnurlauth
 from ..tasks import sse_listeners
 
 
@@ -127,6 +127,8 @@ async def api_payments_pay_invoice():
         return jsonify({"message": str(e)}), HTTPStatus.BAD_REQUEST
     except PermissionError as e:
         return jsonify({"message": str(e)}), HTTPStatus.FORBIDDEN
+    except PaymentFailure as e:
+        return jsonify({"message": str(e)}), 520
     except Exception as exc:
         raise exc