Improve handling of exceptions in commands decorated with @parallel_controllers

Author: albireox

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### 🔧 Fixed
 
 * Copy data returned during fetching to make the array writeable.
+* Improve handling of exceptions in commands decorated with `@parallel_controllers`.
 
 
 ## 0.15.5 - August 29, 2025

archon/actor/tools.py

@@ -105,11 +105,18 @@ async def wrapper(
             if len(pending) > 0:  # pragma: no cover
                 for p in pending:
                     p.cancel()
-                return command.fail("Some tasks raised exceptions.")
-
-            results = [task.result() for task in done]
-            if False in results:
-                return command.fail(error="Some controllers failed.")
+                return command.fail(
+                    "Found pending tasks while running controllers in parallel."
+                )
+
+            for task in done:
+                try:
+                    result = task.result()
+                except Exception as ee:
+                    return command.fail(error=f"Controllers failed with error: {ee}")
+                else:
+                    if result is False:
+                        return command.fail(error="Some controllers failed.")
 
             return command.finish()
 

tests/actor/test_command_reconnect.py

@@ -56,3 +56,15 @@ async def test_reconnect_start_timesout(actor: ArchonActor, mocker):
 
     assert command.status.did_fail
     assert len(command.replies) == 3
+
+
+async def test_reconnect_fails(actor: ArchonActor):
+    # This will make the command fails
+    del actor.controllers["sp1"].name
+
+    command = await actor.invoke_mock_command("reconnect")
+    await command
+
+    assert command.status.did_fail
+    assert len(command.replies) == 2
+    assert "Controllers failed with error" in command.replies[-1].body["error"]