diff --git a/.last-branch b/.last-branch
index 06a5a28..00b87aa 100644
--- a/.last-branch
+++ b/.last-branch
@@ -1 +1 @@
-v20260203-09-autotask-resolution-from-note
+v20260203-10-autotask-resolution-field-aliases
diff --git a/containers/backupchecks/src/backend/app/integrations/autotask/client.py b/containers/backupchecks/src/backend/app/integrations/autotask/client.py
index 3b19942..3622f76 100644
--- a/containers/backupchecks/src/backend/app/integrations/autotask/client.py
+++ b/containers/backupchecks/src/backend/app/integrations/autotask/client.py
@@ -584,22 +584,43 @@ class AutotaskClient:
         if not isinstance(t, dict):
             raise AutotaskError("Autotask did not return a ticket object.")
 
-        stabilising_fields = [
-            "id",
-            "companyID",
-            "queueID",
-            "title",
-            "priority",
-            "status",
-            "dueDateTime",
-            "ticketCategory",
-            "issueType",
-            "subIssueType",
-            "source",
-            "organizationalLevelAssociationID",
-        ]
+        # Some Autotask environments return slightly different field names (e.g. *ID vs *Id).
+        # We always source values from the fresh GET and send the canonical field names in the PUT payload.
+        field_sources: Dict[str, list[str]] = {
+            "id": ["id"],
+            "companyID": ["companyID", "companyId"],
+            "queueID": ["queueID", "queueId"],
+            "title": ["title"],
+            "priority": ["priority"],
+            "status": ["status"],
+            "dueDateTime": ["dueDateTime", "dueDate", "dueDateUtc"],
+            "ticketCategory": ["ticketCategory", "ticketCategoryID", "ticketCategoryId"],
+            "issueType": ["issueType", "issueTypeID", "issueTypeId"],
+            "subIssueType": ["subIssueType", "subIssueTypeID", "subIssueTypeId"],
+            "source": ["source", "sourceID", "sourceId"],
+            "organizationalLevelAssociationID": [
+                "organizationalLevelAssociationID",
+                "organizationalLevelAssociationId",
+            ],
+        }
+
+        def _get_first(ticket_obj: Dict[str, Any], keys: list[str]) -> Any:
+            for k in keys:
+                if k in ticket_obj:
+                    return ticket_obj.get(k)
+            return None
+
+        stabilising_fields = list(field_sources.keys())
+
+        resolved_values: Dict[str, Any] = {}
+        missing: list[str] = []
+        for f in stabilising_fields:
+            v = _get_first(t, field_sources[f])
+            # Treat None/"" as missing, but allow 0 for picklists.
+            if v in (None, ""):
+                missing.append(f)
+            resolved_values[f] = v
 
-        missing = [f for f in stabilising_fields if t.get(f) in (None, "")]
         if missing:
             raise AutotaskError(
                 "Cannot safely update ticket resolution because required fields are missing: " + ", ".join(missing)
@@ -614,11 +635,10 @@ class AutotaskClient:
         else:
             new_res = res_txt
 
-        payload: Dict[str, Any] = {k: t.get(k) for k in stabilising_fields}
-        # Ensure numeric ID is an int for PUT.
-        payload["id"] = int(t.get("id"))
+        payload: Dict[str, Any] = dict(resolved_values)
+        payload["id"] = int(resolved_values.get("id"))
         # Explicitly keep status unchanged.
-        payload["status"] = t.get("status")
+        payload["status"] = resolved_values.get("status")
         payload["resolution"] = new_res
 
         self.update_ticket(payload)
diff --git a/docs/changelog.md b/docs/changelog.md
index 745eae9..9edae79 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -512,6 +512,12 @@ Changes:
 - Resolution updates follow the validated safe pattern: GET the current Ticket first, then PUT with stabilising fields while keeping the status unchanged.
 - Added verification to ensure the resolution text is persisted after the update.
 
+## v20260203-10-autotask-resolution-field-aliases
+
+- Fix: Resolution PUT now always reuses the latest classification/routing fields from GET /Tickets/{id}, including support for common field-name variants (*ID/*Id).
+- Prevents failure when issueType/subIssueType/source are not present under the expected keys after ticket creation or later changes.
+- Keeps ticket status unchanged while updating resolution, per validated Postman contract.
+
 ***
 
 ## v0.1.21