fix: normalize Go zero time in BackupListReturn and ExportStatusReturn completed_at

test/test_backup.py

@@ -39,3 +39,29 @@ def test_list_return_defaults_incremental_base_backup_id_to_none(entry: Dict[str
     # The server omits the field for non-incremental backups, and only populates
     # it for callers it has confirmed as root, so absent must not be an error.
     assert BackupListReturn(**entry).incremental_base_backup_id is None
+
+
+def test_running_backup_and_export_zero_completed_at_is_none() -> None:
+    from weaviate.export.export import ExportStatusReturn
+
+    backup = BackupListReturn(
+        **_list_entry(status="STARTED", completedAt="0001-01-01T00:00:00.000Z")
+    )
+    assert backup.completed_at is None
+
+    completed = BackupListReturn(
+        **_list_entry(status="SUCCESS", completedAt="2026-08-01T10:05:00.000Z")
+    )
+    assert completed.completed_at is not None
+    assert completed.completed_at.year == 2026
+
+    export_status = ExportStatusReturn(
+        id="exp1",
+        backend="filesystem",
+        path="/tmp/exports/exp1",
+        status="TRANSFERRING",
+        startedAt="2026-10-21T06:50:47.995Z",
+        completedAt="0001-01-01T00:00:00.000Z",
+        classes=["Article"],
+    )
+    assert export_status.completed_at is None

weaviate/backup/backup.py

@@ -2,7 +2,7 @@
 from enum import Enum
 from typing import Any, Dict, List, Optional, cast
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from weaviate.backup.backup_location import _BackupLocationConfig
 
@@ -107,3 +107,10 @@ class BackupListReturn(BaseModel):
     # None when the backup is not incremental, and also when the server omits the
     # field: it is only returned to callers Weaviate has confirmed as root.
     incremental_base_backup_id: Optional[str] = Field(default=None)
+
+    @field_validator("completed_at", mode="after")
+    @classmethod
+    def _normalize_zero_completed_at(cls, v: Optional[datetime]) -> Optional[datetime]:
+        if v is not None and v.year <= 1:
+            return None
+        return v

weaviate/export/export.py

@@ -4,7 +4,7 @@
 from enum import Enum
 from typing import Dict, List, Optional
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from weaviate.backup.backup import BackupStorage
 
@@ -69,3 +69,10 @@ class ExportStatusReturn(ExportCreateReturn):
     )
     error: Optional[str] = None
     took_in_ms: Optional[int] = Field(alias="tookInMs", default=None)
+
+    @field_validator("completed_at", mode="after")
+    @classmethod
+    def _normalize_zero_completed_at(cls, v: Optional[datetime]) -> Optional[datetime]:
+        if v is not None and v.year <= 1:
+            return None
+        return v