diff --git a/antarest/study/storage/variantstudy/business/utils.py b/antarest/study/storage/variantstudy/business/utils.py
index 6f04601ec5..933c72bed7 100644
--- a/antarest/study/storage/variantstudy/business/utils.py
+++ b/antarest/study/storage/variantstudy/business/utils.py
@@ -52,10 +52,13 @@ def get_or_create_section(json_ini: JSON, section: str) -> JSON:
 
 
 def remove_none_args(command_dto: CommandDTO) -> CommandDTO:
-    if isinstance(command_dto.args, list):
-        command_dto.args = [{k: v for k, v in args.items() if v is not None} for args in command_dto.args]
+    args = command_dto.args
+    if isinstance(args, list):
+        command_dto.args = [{k: v for k, v in args.items() if v is not None} for args in args]
+    elif isinstance(args, dict):
+        command_dto.args = {k: v for k, v in args.items() if v is not None}
     else:
-        command_dto.args = {k: v for k, v in command_dto.args.items() if v is not None}
+        raise TypeError(f"Invalid type for args: {type(args)}")
     return command_dto
 
 
diff --git a/antarest/study/storage/variantstudy/model/model.py b/antarest/study/storage/variantstudy/model/model.py
index 1e51032ce4..cd478742b4 100644
--- a/antarest/study/storage/variantstudy/model/model.py
+++ b/antarest/study/storage/variantstudy/model/model.py
@@ -1,4 +1,4 @@
-from typing import List, Optional, Tuple, Union
+import typing as t
 
 from pydantic import BaseModel
 
@@ -7,28 +7,63 @@
 
 
 class GenerationResultInfoDTO(BaseModel):
+    """
+    Result information of a snapshot generation process.
+
+    Attributes:
+        success: A boolean indicating whether the generation process was successful.
+        details: A list of tuples containing detailed information about the generation process.
+    """
+
     success: bool
-    details: List[Tuple[str, bool, str]]
+    details: t.MutableSequence[t.Tuple[str, bool, str]]
 
 
 class CommandDTO(BaseModel):
-    id: Optional[str]
+    """
+    This class represents a command.
+
+    Attributes:
+        id: The unique identifier of the command.
+        action: The action to be performed by the command.
+        args: The arguments for the command action.
+        version: The version of the command.
+    """
+
+    id: t.Optional[str]
     action: str
-    # if args is a list, this mean the command will be mapped to the list of args
-    args: Union[List[JSON], JSON]
+    args: t.Union[t.MutableSequence[JSON], JSON]
     version: int = 1
 
 
 class CommandResultDTO(BaseModel):
+    """
+    This class represents the result of a command.
+
+    Attributes:
+        study_id: The unique identifier of the study.
+        id: The unique identifier of the command.
+        success: A boolean indicating whether the command was successful.
+        message: A message detailing the result of the command.
+    """
+
     study_id: str
     id: str
     success: bool
     message: str
 
 
-class VariantTreeDTO(BaseModel):
-    node: StudyMetadataDTO
-    children: List["VariantTreeDTO"]
+class VariantTreeDTO:
+    """
+    This class represents a variant tree structure.
 
+    Attributes:
+        node: The metadata of the study (ID, name, version, etc.).
+        children: A list of variant children.
+    """
 
-VariantTreeDTO.update_forward_refs()
+    def __init__(self, node: StudyMetadataDTO, children: t.MutableSequence["VariantTreeDTO"]) -> None:
+        # We are intentionally not using Pydantic’s `BaseModel` here to prevent potential
+        # `RecursionError` exceptions that can occur with Pydantic versions before v2.
+        self.node = node
+        self.children = children or []
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 89da140393..977d760fb6 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -13,6 +13,8 @@ v2.16.8 (unreleased)
 * **st-storages (ui):** correction of incorrect wording between "withdrawal" and "injection" [`#1977`](https://github.com/AntaresSimulatorTeam/AntaREST/pull/1977)
 * **st-storages (ui):** change matrix titles [`#1994`](https://github.com/AntaresSimulatorTeam/AntaREST/pull/1994)
 * **st-storages:** use command when updating matrices [`#1971`](https://github.com/AntaresSimulatorTeam/AntaREST/pull/1971)
+* **variants:** avoid recursive error when creating big variant tree [`#1967`](https://github.com/AntaresSimulatorTeam/AntaREST/pull/1967)
+
 
 v2.16.7 (2024-03-05)
 --------------------
diff --git a/tests/integration/studies_blueprint/test_synthesis.py b/tests/integration/studies_blueprint/test_synthesis.py
index 70f5f0c907..aa6141e782 100644
--- a/tests/integration/studies_blueprint/test_synthesis.py
+++ b/tests/integration/studies_blueprint/test_synthesis.py
@@ -58,7 +58,7 @@ def test_raw_study(
         )
         assert res.status_code == 200, res.json()
         duration = time.time() - start
-        assert 0 <= duration <= 0.1, f"Duration is {duration} seconds"
+        assert 0 <= duration <= 0.3, f"Duration is {duration} seconds"
 
     def test_variant_study(
         self,
diff --git a/tests/integration/variant_blueprint/test_variant_manager.py b/tests/integration/variant_blueprint/test_variant_manager.py
index 5af256dbbe..9d5be37e2b 100644
--- a/tests/integration/variant_blueprint/test_variant_manager.py
+++ b/tests/integration/variant_blueprint/test_variant_manager.py
@@ -186,3 +186,44 @@ def test_variant_manager(client: TestClient, admin_access_token: str, study_id:
 
         res = client.get(f"/v1/studies/{variant_id}", headers=admin_headers)
         assert res.status_code == 404
+
+
+def test_comments(client: TestClient, admin_access_token: str, variant_id: str) -> None:
+    admin_headers = {"Authorization": f"Bearer {admin_access_token}"}
+
+    # Put comments
+    comment = "updated comment"
+    res = client.put(f"/v1/studies/{variant_id}/comments", json={"comments": comment}, headers=admin_headers)
+    assert res.status_code == 204
+
+    # Asserts comments are updated
+    res = client.get(f"/v1/studies/{variant_id}/comments", headers=admin_headers)
+    assert res.json() == comment
+
+    # Generates the study
+    res = client.put(f"/v1/studies/{variant_id}/generate?denormalize=false&from_scratch=true", headers=admin_headers)
+    task_id = res.json()
+    # Wait for task completion
+    res = client.get(f"/v1/tasks/{task_id}", headers=admin_headers, params={"wait_for_completion": True})
+    assert res.status_code == 200
+    task_result = TaskDTO.parse_obj(res.json())
+    assert task_result.status == TaskStatus.COMPLETED
+    assert task_result.result is not None
+    assert task_result.result.success
+
+    # Asserts comments did not disappear
+    res = client.get(f"/v1/studies/{variant_id}/comments", headers=admin_headers)
+    assert res.json() == comment
+
+
+def test_recursive_variant_tree(client: TestClient, admin_access_token: str):
+    admin_headers = {"Authorization": f"Bearer {admin_access_token}"}
+    base_study_res = client.post("/v1/studies?name=foo", headers=admin_headers)
+    base_study_id = base_study_res.json()
+    parent_id = base_study_res.json()
+    for k in range(150):
+        res = client.post(f"/v1/studies/{base_study_id}/variants?name=variant_{k}", headers=admin_headers)
+        base_study_id = res.json()
+    # Asserts that we do not trigger a Recursive Exception
+    res = client.get(f"/v1/studies/{parent_id}/variants", headers=admin_headers)
+    assert res.status_code == 200