diff --git a/src/ert/analysis/_es_update.py b/src/ert/analysis/_es_update.py
index 09cefa4965e..d3fd977f24d 100644
--- a/src/ert/analysis/_es_update.py
+++ b/src/ert/analysis/_es_update.py
@@ -862,6 +862,8 @@ def analysis_IES(
     # This is needed for the SIES library
     masking_of_initial_parameters = ens_mask[initial_mask]
 
+    updated_parameter_groups = []
+
     # It is not the iterations relating to IES or ESMDA.
     # It is related to functionality for turning on/off groups of parameters and observations.
     for update_step in update_config: