diff --git a/auto_update.py b/auto_update.py
index aff54bc..2c26aa9 100644
--- a/auto_update.py
+++ b/auto_update.py
@@ -1,27 +1,88 @@
 import os
+import re
 import requests
 from ruamel.yaml import YAML
 
-def get_latest_grid_driver():
-    # URL of the JSON file containing driver information
-    url = "https://raw.githubusercontent.com/Azure/azhpc-extensions/refs/heads/master/NvidiaGPU/Nvidia-GPU-Linux-Resources.json"
-    response = requests.get(url)
-    response.raise_for_status()  
+# Source of truth for Azure-mirrored NVIDIA GRID drivers. resources.json
+# contains all currently-supported NVIDIA driver branches (we previously
+# read Nvidia-GPU-Linux-Resources.json, but that file is no longer updated
+# past 550.144.06 / vGPU 17.55).
+RESOURCES_JSON_URL = (
+    "https://raw.githubusercontent.com/Azure/azhpc-extensions/"
+    "refs/heads/master/NvidiaGPU/resources.json"
+)
+
+# Driver versions look like "570.211.01" — major.minor.patch. The MAJOR
+# component corresponds to NVIDIA's driver branch (R570, R580, …) and is
+# the ABI-stable boundary: within one major, NVIDIA only ships
+# bug-fix / patch releases. Crossing a major (e.g. 570 -> 580) can
+# introduce kernel-module ABI changes, install-script differences, and
+# vGPU licensing changes, so it requires deliberate validation.
+DRIVER_VERSION_PATTERN = re.compile(r"^\d+(?:\.\d+){1,2}$")
+
+
+def _driver_sort_key(version_str):
+    """Convert "570.211.01" -> (570, 211, 1) so version comparisons are numeric."""
+    return tuple(int(p) for p in version_str.split(".") if p.isdigit())
+
+
+def _current_driver_major(config):
+    """Return the driver major (e.g. '570') of the currently-pinned grid version."""
+    current = str(config.get("grid", {}).get("version", "")).strip()
+    if not DRIVER_VERSION_PATTERN.match(current):
+        raise RuntimeError(
+            f"Cannot determine driver major from grid.version={current!r} "
+            f"in driver_config.yml (expected like '570.211.01')."
+        )
+    return current.split(".")[0]
+
+
+def get_latest_grid_driver_for_major(target_major):
+    """Return (driver_version, download_url) for the highest version in
+    resources.json whose driver major matches target_major.
+
+    Walks OS.Linux.Version[*].Driver[*] for Type='GRID' blocks and keeps any
+    entry whose Num starts with f"{target_major}.". Falls back from DirLink
+    to FwLink so we still get a usable URL when the manifest puts the
+    download in FwLink (the v18.5 entry is one such example).
+    """
+    response = requests.get(RESOURCES_JSON_URL, timeout=30)
+    response.raise_for_status()
     data = response.json()
-    
-    # Extract the latest GRID driver information
-    grid_versions = data['Latest']['Category']
-    grid_info = next((item for item in grid_versions if item["Name"] == "GRID"), None)
-    
-    if grid_info:
-        latest_version_info = grid_info['Versions'][0]
-        latest_version = latest_version_info['DriverVersion']
-        latest_url = latest_version_info['Driver'][0]['DirLink']
-        return latest_version, latest_url
-    
-    raise Exception("Could not find latest GRID driver version")
-
-# Add this at the end of your update_driver_config function
+
+    linux_block = next(
+        (o for o in data.get("OS", []) if o.get("Name") == "Linux"), None
+    )
+    if linux_block is None:
+        raise RuntimeError("No 'Linux' OS block in NvidiaGPU/resources.json")
+
+    prefix = f"{target_major}."
+    candidates = {}
+    for distro in linux_block.get("Version", []):
+        for drv_block in distro.get("Driver", []):
+            if drv_block.get("Type") != "GRID":
+                continue
+            for v in drv_block.get("Version", []):
+                num = str(v.get("Num", "")).strip()
+                if not num.startswith(prefix):
+                    continue
+                url = v.get("DirLink") or v.get("FwLink")
+                if not url:
+                    continue
+                # Same driver may appear in multiple distro blocks; first wins.
+                candidates.setdefault(num, url)
+
+    if not candidates:
+        raise RuntimeError(
+            f"No GRID driver {target_major}.x entries found in "
+            f"{RESOURCES_JSON_URL}. If NVIDIA has ended patches for this "
+            f"branch, bump driver_config.yml to the next major manually."
+        )
+
+    best = max(candidates, key=_driver_sort_key)
+    return best, candidates[best]
+
+
 def update_driver_config():
     yaml = YAML()
     yaml.preserve_quotes = True
@@ -29,18 +90,16 @@ def update_driver_config():
 
     if not os.path.exists("driver_config.yml"):
         raise FileNotFoundError("driver_config.yml not found in the current directory.")
-    
+
     with open("driver_config.yml", "r") as f:
         config = yaml.load(f)
-    
-    # Get latest version and URL
-    latest_version, latest_url = get_latest_grid_driver()
-    
-    # Update the grid section while preserving order
+
+    target_major = _current_driver_major(config)
+    latest_version, latest_url = get_latest_grid_driver_for_major(target_major)
+
     config['grid']['version'] = latest_version
     config['grid']['url'] = latest_url
-    
-    # Write back to file
+
     with open("driver_config.yml", "w") as f:
         yaml.dump(config, f)