diff --git a/lib/iris/src/iris/cluster/client/job_info.py b/lib/iris/src/iris/cluster/client/job_info.py
index 38f33854f4..5d10b5d385 100644
--- a/lib/iris/src/iris/cluster/client/job_info.py
+++ b/lib/iris/src/iris/cluster/client/job_info.py
@@ -104,7 +104,8 @@ def get_job_info() -> JobInfo | None:
         constraints: list[Constraint] = []
         if constraints_json:
             for item in json.loads(constraints_json):
-                constraints.append(Constraint.from_proto(json_format.ParseDict(item, cluster_pb2.Constraint())))
+                proto = json_format.ParseDict(item, cluster_pb2.Constraint(), ignore_unknown_fields=True)
+                constraints.append(Constraint.from_proto(proto))
 
         info = JobInfo(
             task_id=task_id,
diff --git a/lib/iris/tests/cluster/client/test_job_info.py b/lib/iris/tests/cluster/client/test_job_info.py
index 5d09f1f67e..4c2da54a58 100644
--- a/lib/iris/tests/cluster/client/test_job_info.py
+++ b/lib/iris/tests/cluster/client/test_job_info.py
@@ -1,6 +1,8 @@
 # Copyright The Marin Authors
 # SPDX-License-Identifier: Apache-2.0
 
+import json
+
 from iris.cluster.client.job_info import JobInfo, get_job_info, resolve_job_user, set_job_info
 from iris.cluster.types import JobName
 
@@ -57,3 +59,26 @@ def test_worker_region_absent_when_env_not_set(monkeypatch):
     assert info is not None
     assert info.worker_region is None
     set_job_info(None)
+
+
+def test_constraints_with_unknown_fields_in_json(monkeypatch):
+    """get_job_info tolerates unknown fields in IRIS_JOB_CONSTRAINTS JSON."""
+    set_job_info(None)
+    monkeypatch.setenv("IRIS_TASK_ID", "/test-user/my-job/0:1")
+    constraints_json = json.dumps(
+        [
+            {
+                "key": "region",
+                "op": "CONSTRAINT_OP_EQ",
+                "value": {"string_value": "us-central2"},
+                "unknown_future_field": "some_value",
+            }
+        ]
+    )
+    monkeypatch.setenv("IRIS_JOB_CONSTRAINTS", constraints_json)
+    info = get_job_info()
+    assert info is not None
+    assert len(info.constraints) == 1
+    assert info.constraints[0].key == "region"
+    assert info.constraints[0].value == "us-central2"
+    set_job_info(None)