From cb395058281bb1b18ae23c034c790f055784f535 Mon Sep 17 00:00:00 2001
From: Bouwe Andela <b.andela@esciencecenter.nl>
Date: Fri, 17 Apr 2026 13:49:10 +0200
Subject: [PATCH] Avoid issue with "coordinates"

---
 esmvalcore/iris_helpers.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/esmvalcore/iris_helpers.py b/esmvalcore/iris_helpers.py
index 18db216a09..0170ed2a01 100644
--- a/esmvalcore/iris_helpers.py
+++ b/esmvalcore/iris_helpers.py
@@ -614,6 +614,13 @@ def dataset_to_iris(
     if isinstance(dataset, xr.Dataset):
         conversion_func = ncdata.iris_xarray.cubes_from_xarray
         ds_coords = dataset.coords
+        dataset = dataset.copy(deep=False)
+        # xarray uses a "coordinates" attribute to store the names of
+        # non-dimensional coordinates, but this is not compatible with iris.
+        non_index_coord_vars = tuple(
+            name for name in dataset.coords if name not in dataset.xindexes
+        )
+        dataset = dataset.reset_coords(non_index_coord_vars)
     elif isinstance(dataset, ncdata.NcData):
         conversion_func = ncdata.iris.to_iris
         ds_coords = dataset.variables