diff --git a/src/ert/dark_storage/endpoints/experiment_server.py b/src/ert/dark_storage/endpoints/experiment_server.py
index 84f57ef15cd..dafc174d49e 100644
--- a/src/ert/dark_storage/endpoints/experiment_server.py
+++ b/src/ert/dark_storage/endpoints/experiment_server.py
@@ -338,7 +338,7 @@ async def run(self) -> None:
 
                 if isinstance(item, EndEvent):
                     # Wait for subscribers to receive final events
-                    for sub in shared_data.subscribers.values():
+                    for sub in list(shared_data.subscribers.values()):
                         await sub.is_done()
                     break
             await simulation_future