No JSON could be decoded error.

CHANGELOG.rst

@@ -17,6 +17,7 @@ This document describes changes between each past release.
 
 - Fix retry behaviour when responses are successful (fixes #129)
 - Fix Retry-After value to be read as integer rather than string. (#131)
+- Fix No JSON could be decoded ValueError (fixes #116)
 
 **Internal changes**
 

kinto_http/session.py

@@ -96,7 +96,11 @@ def request(self, method, endpoint, data=None, permissions=None,
                     continue
 
                 # Retries exhausted, raise expection.
-                message = '{0} - {1}'.format(resp.status_code, resp.json())
+                try:
+                    message = '{0} - {1}'.format(resp.status_code, resp.json())
+                except ValueError:
+                    # In case the response is not JSON, fallback to text.
+                    message = '{0} - {1}'.format(resp.status_code, resp.text)
                 exception = KintoException(message)
                 exception.request = resp.request
                 exception.response = resp

kinto_http/tests/test_session.py

@@ -41,6 +41,17 @@ def test_bad_http_status_raises_exception(self):
 
         self.assertRaises(KintoException, session.request, 'get', '/test')
 
+    def test_bad_http_status_raises_exception_even_in_case_of_invalid_json_response(self):
+        response = fake_response(502)
+        response.json.side_effect = ValueError
+        response.text = "Foobar"
+        self.requests_mock.request.return_value = response
+        session = Session('https://example.org')
+
+        with pytest.raises(KintoException) as e:
+            session.request('get', '/test')
+        self.assertEqual(e.value.message, "502 - Foobar")
+
     def test_session_injects_auth_on_requests(self):
         response = fake_response(200)
         self.requests_mock.request.return_value = response