From 95e71ed911332093f61c0df804dd01a84b5c0ea9 Mon Sep 17 00:00:00 2001
From: Shruti Patel <shrutipatel@meta.com>
Date: Wed, 11 Mar 2026 18:12:17 -0700
Subject: [PATCH] Include exception message in ErrorAnalysisCard subtitle
 (#4982)

Summary:

Currently, the subtitle only shows a generic message like "AnalysisNotApplicableStateError encountered while computing ParallelCoordinatesPlot." Show the actual exception message, such as "AnalysisNotApplicableStateError: Experiment has no trials", providing immediate context.

The exception message can now be displayed in the ErrorAnalysisCard subtitle, allowing users to immediately see the reasoning (e.g., why an analysis is not applicable).

Reviewed By: bernardbeckerman

Differential Revision: D94617700
---
 ax/analysis/analysis.py            | 10 +++++++-
 ax/analysis/tests/test_analysis.py | 37 ++++++++++++++++++++++++++++++
 ax/api/tests/test_client.py        |  8 +------
 3 files changed, 47 insertions(+), 8 deletions(-)
 create mode 100644 ax/analysis/tests/test_analysis.py

diff --git a/ax/analysis/analysis.py b/ax/analysis/analysis.py
index ee76d61eb24..cacd2b077f2 100644
--- a/ax/analysis/analysis.py
+++ b/ax/analysis/analysis.py
@@ -206,10 +206,18 @@ def error_card_from_analysis_e(
     analysis_name = analysis_e.analysis.__class__.__name__
     exception_name = analysis_e.exception.__class__.__name__
 
+    # Include the exception message in the subtitle if available, so users can
+    # see the reasoning in the error card.
+    subtitle = (
+        f"{exception_name}: {exception_message}"
+        if (exception_message := str(analysis_e.exception))
+        else f"{exception_name} encountered while computing {analysis_name}."
+    )
+
     return ErrorAnalysisCard(
         name=analysis_name,
         title=f"{analysis_name} Error",
-        subtitle=f"{exception_name} encountered while computing {analysis_name}.",
+        subtitle=subtitle,
         df=pd.DataFrame(),
         blob=analysis_e.tb_str() or "",
     )
diff --git a/ax/analysis/tests/test_analysis.py b/ax/analysis/tests/test_analysis.py
new file mode 100644
index 00000000000..caf60d5851f
--- /dev/null
+++ b/ax/analysis/tests/test_analysis.py
@@ -0,0 +1,37 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+# pyre-strict
+
+from ax.analysis.analysis import AnalysisE, error_card_from_analysis_e
+from ax.analysis.plotly.parallel_coordinates import ParallelCoordinatesPlot
+from ax.utils.common.testutils import TestCase
+
+
+class AnalysisTest(TestCase):
+    def test_error_card_from_analysis_e(self) -> None:
+        for exception, expected_subtitle in (
+            (
+                ValueError("something went wrong"),
+                "ValueError: something went wrong",
+            ),
+            (
+                ValueError(),
+                "ValueError encountered while computing ParallelCoordinatesPlot.",
+            ),
+        ):
+            with self.subTest(exception=exception):
+                analysis_e = AnalysisE(
+                    message="test",
+                    exception=exception,
+                    analysis=ParallelCoordinatesPlot(),
+                )
+
+                card = error_card_from_analysis_e(analysis_e)
+
+                self.assertEqual(card.name, "ParallelCoordinatesPlot")
+                self.assertEqual(card.title, "ParallelCoordinatesPlot Error")
+                self.assertEqual(card.subtitle, expected_subtitle)
+                self.assertIn("ValueError", card.blob)
diff --git a/ax/api/tests/test_client.py b/ax/api/tests/test_client.py
index 49f764e0bbb..afa38da272e 100644
--- a/ax/api/tests/test_client.py
+++ b/ax/api/tests/test_client.py
@@ -23,7 +23,6 @@
 from ax.api.protocols.metric import IMetric
 from ax.api.protocols.runner import IRunner
 from ax.api.types import TParameterization
-from ax.core.analysis_card import AnalysisCard
 from ax.core.data import Data
 from ax.core.experiment import Experiment
 from ax.core.map_metric import MapMetric
@@ -1280,12 +1279,7 @@ def test_compute_analyses(self) -> None:
         self.assertEqual(cards[0].title, "ParallelCoordinatesPlot Error")
         self.assertEqual(
             cards[0].subtitle,
-            "AnalysisNotApplicableStateError encountered while computing "
-            "ParallelCoordinatesPlot.",
-        )
-        self.assertIn(
-            "Experiment has no trials",
-            assert_is_instance(cards[0], AnalysisCard).blob,
+            "AnalysisNotApplicableStateError: Experiment has no trials.",
         )
 
         for trial_index, _ in client.get_next_trials(max_trials=1).items():