make action server connection error message more descriptive (#11123)

* make action server connection error message more descriptive

changelog/11123.misc.md

@@ -0,0 +1 @@
+Make the exception message raised when the action server is unreachable more descriptive.

rasa/core/actions/action.py

@@ -762,15 +762,21 @@ async def run(
                 logger.error(exception.message)
                 raise exception
             else:
-                raise RasaException("Failed to execute custom action.") from e
+                raise RasaException(
+                    f"Failed to execute custom action '{self.name()}'"
+                ) from e
 
         except aiohttp.ClientConnectionError as e:
             logger.error(
-                "Failed to run custom action '{}'. Couldn't connect "
-                "to the server at '{}'. Is the server running? "
-                "Error: {}".format(self.name(), self.action_endpoint.url, e)
+                f"Failed to run custom action '{self.name()}'. Couldn't connect "
+                f"to the server at '{self.action_endpoint.url}'. "
+                f"Is the server running? "
+                f"Error: {e}"
+            )
+            raise RasaException(
+                f"Failed to execute custom action '{self.name()}'. Couldn't connect "
+                f"to the server at '{self.action_endpoint.url}."
             )
-            raise RasaException("Failed to execute custom action.")
 
         except aiohttp.ClientError as e:
             # not all errors have a status attribute, but

tests/core/test_actions.py

@@ -548,7 +548,7 @@ async def test_remote_action_endpoint_not_running(
 
     with pytest.raises(Exception) as execinfo:
         await remote_action.run(default_channel, default_nlg, default_tracker, domain)
-    assert "Failed to execute custom action." in str(execinfo.value)
+    assert "Failed to execute custom action" in str(execinfo.value)
 
 
 async def test_remote_action_endpoint_responds_500(
@@ -564,7 +564,7 @@ async def test_remote_action_endpoint_responds_500(
             await remote_action.run(
                 default_channel, default_nlg, default_tracker, domain
             )
-        assert "Failed to execute custom action." in str(execinfo.value)
+        assert "Failed to execute custom action" in str(execinfo.value)
 
 
 async def test_remote_action_endpoint_responds_400(