diff --git a/app/routing/middleware/SAMLRequest.middleware.js b/app/routing/middleware/SAMLRequest.middleware.js
index f0db6b4..7881b90 100644
--- a/app/routing/middleware/SAMLRequest.middleware.js
+++ b/app/routing/middleware/SAMLRequest.middleware.js
@@ -17,7 +17,9 @@ class SAMLRequestMiddleware extends Middleware {
                 // Verify that the issuer is known
                 const sp = await ServiceProvider.findOne({entity_id: data.issuer, active: true})
                 if (!sp)
-                    return res.error(401, 'Unable to continue. The SAML issuer is unknown.')
+                    return res.error(401, {
+                        message: 'Unable to continue. The SAML issuer is unknown.'
+                    })
 
                 req.saml_request = {
                     relay_state: req.query.RelayState || req.body.RelayState,