diff --git a/src/ert/analysis/_es_update.py b/src/ert/analysis/_es_update.py
index 45c2bd69624..fde8e11cf6d 100644
--- a/src/ert/analysis/_es_update.py
+++ b/src/ert/analysis/_es_update.py
@@ -261,6 +261,10 @@ def _load_observations_and_responses(
         iens_active_index,
     )
 
+    observations_and_responses = observations_and_responses.sort(
+        by=["observation_key", "index"]
+    )
+
     S = observations_and_responses.select(
         observations_and_responses.columns[5:]
     ).to_numpy()
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_only_using_subset_observations/0/update_log b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_only_using_subset_observations/0/update_log
index 0bddd5859fe..ef3df8838e6 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_only_using_subset_observations/0/update_log
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_only_using_subset_observations/0/update_log
@@ -1,6 +1,6 @@
 ----------  ---------  -----  -----  -----  -----  ------  -----  ------
-WPR_DIFF_1  199, 400   0.000  0.100  1.000  0.100  -0.011  0.060  Active
-WPR_DIFF_1  199, 800   0.100  0.200  1.000  0.200   0.081  0.126  Active
 WPR_DIFF_1  199, 1200  0.200  0.150  1.000  0.150   0.073  0.130  Active
 WPR_DIFF_1  199, 1800  0.000  0.050  1.000  0.050   0.127  0.125  Active
+WPR_DIFF_1  199, 400   0.000  0.100  1.000  0.100  -0.011  0.060  Active
+WPR_DIFF_1  199, 800   0.100  0.200  1.000  0.200   0.081  0.126  Active
 ----------  ---------  -----  -----  -----  -----  ------  -----  ------
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess0/update_log b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess0/update_log
index 410d07519a4..c3046ca1832 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess0/update_log
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess0/update_log
@@ -205,8 +205,8 @@ WOPR_OP1_190  2015-03-15 00:00:00.000  0.015  0.010  1.732  0.017   0.042  0.041
 WOPR_OP1_36   2010-12-26 00:00:00.000  0.700  0.070  1.732  0.121   0.650  0.084  Active
 WOPR_OP1_72   2011-12-21 00:00:00.000  0.500  0.050  1.000  0.050   0.405  0.170  Active
 WOPR_OP1_9    2010-03-31 00:00:00.000  0.100  0.050  1.732  0.087   0.096  0.060  Active
-WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
-WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 WPR_DIFF_1    199, 1200                0.200  0.150  1.000  0.150   0.073  0.130  Active
 WPR_DIFF_1    199, 1800                0.000  0.050  1.000  0.050   0.127  0.125  Active
+WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
+WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 ------------  -----------------------  -----  -----  -----  -----  ------  -----  ------
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess1/update_log b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess1/update_log
index a0bd117d407..bf5df079e89 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess1/update_log
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess1/update_log
@@ -205,8 +205,8 @@ WOPR_OP1_190  2015-03-15 00:00:00.000  0.015  0.010  1.000  0.010   0.042  0.041
 WOPR_OP1_36   2010-12-26 00:00:00.000  0.700  0.070  1.000  0.070   0.650  0.084  Active
 WOPR_OP1_72   2011-12-21 00:00:00.000  0.500  0.050  1.000  0.050   0.405  0.170  Active
 WOPR_OP1_9    2010-03-31 00:00:00.000  0.100  0.050  1.000  0.050   0.096  0.060  Active
-WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
-WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 WPR_DIFF_1    199, 1200                0.200  0.150  1.000  0.150   0.073  0.130  Active
 WPR_DIFF_1    199, 1800                0.000  0.050  1.000  0.050   0.127  0.125  Active
+WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
+WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 ------------  -----------------------  -----  -----  -----  -----  ------  -----  ------
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess2/update_log b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess2/update_log
index 185252417e0..1d889e46ebe 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess2/update_log
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess2/update_log
@@ -205,8 +205,8 @@ WOPR_OP1_190  2015-03-15 00:00:00.000  0.015  0.010  1.000  0.010   0.042  0.041
 WOPR_OP1_36   2010-12-26 00:00:00.000  0.700  0.070  1.000  0.070   0.650  0.084  Active
 WOPR_OP1_72   2011-12-21 00:00:00.000  0.500  0.050  1.000  0.050   0.405  0.170  Active
 WOPR_OP1_9    2010-03-31 00:00:00.000  0.100  0.050  1.000  0.050   0.096  0.060  Active
-WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
-WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 WPR_DIFF_1    199, 1200                0.200  0.150  1.000  0.150   0.073  0.130  Active
 WPR_DIFF_1    199, 1800                0.000  0.050  1.000  0.050   0.127  0.125  Active
+WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
+WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 ------------  -----------------------  -----  -----  -----  -----  ------  -----  ------
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess3/update_log b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess3/update_log
index 6023b63ed2d..f0d91911faf 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess3/update_log
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report/0-misfit_preprocess3/update_log
@@ -205,8 +205,8 @@ WOPR_OP1_190  2015-03-15 00:00:00.000  0.015  0.010  1.414  0.014   0.042  0.041
 WOPR_OP1_36   2010-12-26 00:00:00.000  0.700  0.070  1.000  0.070   0.650  0.084  Active
 WOPR_OP1_72   2011-12-21 00:00:00.000  0.500  0.050  1.000  0.050   0.405  0.170  Active
 WOPR_OP1_9    2010-03-31 00:00:00.000  0.100  0.050  1.000  0.050   0.096  0.060  Active
-WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
-WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 WPR_DIFF_1    199, 1200                0.200  0.150  1.000  0.150   0.073  0.130  Active
 WPR_DIFF_1    199, 1800                0.000  0.050  1.000  0.050   0.127  0.125  Active
+WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Active
+WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Active
 ------------  -----------------------  -----  -----  -----  -----  ------  -----  ------
diff --git a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report_with_exception_in_analysis_ES/0/error_event b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report_with_exception_in_analysis_ES/0/error_event
index 1f51a76e394..eaa94298638 100644
--- a/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report_with_exception_in_analysis_ES/0/error_event
+++ b/tests/ert/unit_tests/analysis/snapshots/test_es_update/test_update_report_with_exception_in_analysis_ES/0/error_event
@@ -205,8 +205,8 @@ WOPR_OP1_190  2015-03-15 00:00:00.000  0.015  0.010  1.000  0.010   0.042  0.041
 WOPR_OP1_36   2010-12-26 00:00:00.000  0.700  0.070  1.000  0.070   0.650  0.084  Deactivated, outlier
 WOPR_OP1_72   2011-12-21 00:00:00.000  0.500  0.050  1.000  0.050   0.405  0.170  Deactivated, outlier
 WOPR_OP1_9    2010-03-31 00:00:00.000  0.100  0.050  1.000  0.050   0.096  0.060  Deactivated, outlier
-WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Deactivated, outlier
-WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Deactivated, outlier
 WPR_DIFF_1    199, 1200                0.200  0.150  1.000  0.150   0.073  0.130  Deactivated, outlier
 WPR_DIFF_1    199, 1800                0.000  0.050  1.000  0.050   0.127  0.125  Deactivated, outlier
+WPR_DIFF_1    199, 400                 0.000  0.100  1.000  0.100  -0.011  0.060  Deactivated, outlier
+WPR_DIFF_1    199, 800                 0.100  0.200  1.000  0.200   0.081  0.126  Deactivated, outlier
 ------------  -----------------------  -----  -----  -----  -----  ------  -----  --------------------
diff --git a/tests/ert/unit_tests/analysis/test_es_update.py b/tests/ert/unit_tests/analysis/test_es_update.py
index 14cc02d125e..4767948e9b6 100644
--- a/tests/ert/unit_tests/analysis/test_es_update.py
+++ b/tests/ert/unit_tests/analysis/test_es_update.py
@@ -222,31 +222,31 @@ def test_update_report_with_different_observation_status_from_smoother_update(
         (
             "IES_ENKF",
             [
-                0.5167529669896218,
-                -0.9178847938402281,
-                -0.6299046429604261,
-                -0.1632005925319205,
-                0.0216488942750398,
-                0.07464619425897459,
-                -1.5587692532545538,
-                0.22910522740018124,
-                -0.7171489000139469,
-                0.7287252249699406,
+                0.6038000995616932,
+                -0.8995579663087738,
+                -0.650440718033405,
+                -0.11664520562571357,
+                0.14637004546145008,
+                0.06369104020984925,
+                -1.5673340724477953,
+                0.2045320804879709,
+                -0.8182935847537811,
+                0.7551499933992224,
             ],
         ),
         (
             "STD_ENKF",
             [
-                1.3040645145742686,
-                -0.8162878122658299,
-                -1.5484856041224397,
-                -1.379896334985399,
-                -0.510970027650022,
-                0.5638868158813687,
-                -2.7669280724377487,
-                1.7160680670028017,
-                -1.2603717378211836,
-                1.2014197463741136,
+                1.7365584618531105,
+                -0.819068074727709,
+                -1.6628460358849138,
+                -1.269803440396085,
+                -0.06688718485326725,
+                0.5544021609832737,
+                -2.904293766981197,
+                1.6866443742416257,
+                -1.6783511959093573,
+                1.3081213916230614,
             ],
         ),
     ],
@@ -325,7 +325,7 @@ def test_update_snapshot(
     assert sim_gen_kw != target_gen_kw
 
     # Check that posterior is as expected
-    assert target_gen_kw == pytest.approx(expected_gen_kw, rel=1e-5)
+    assert target_gen_kw == pytest.approx(expected_gen_kw, abs=1e-5)
 
 
 @pytest.mark.usefixtures("use_tmpdir")