While the feature is useful, the constant notification can be disruptive. Users report seeing this message every few minutes, even when they aren't editing blocks.
(defun C:UpdateFromHost ( / hostPath blockName) (setq hostPath "\\\\NetworkDrive\\CAD_Library\\Corporate_Blocks_2025.dwg") (command "-INSERT" (strcat "*" hostPath) "0,0" "1" "1" "0") (command "ERASE" "L" "") (princ "\nAll block definitions reloaded from host file.") )
If your company policy or setup requires you to edit and lock down the hosts file to manage your AutoCAD environment, follow the steps below to successfully update and block it. Step-by-Step Guide to Updating and Securing the HOSTS File
Here is a comprehensive guide to understanding why this happens and how to resolve it safely. What Does "AutoCAD Block Host File" Mean?
Sometimes, a drawing contains two blocks with the same name (one defined internally, one referenced externally). AutoCAD attempts to reconcile these by updating the host file to match the primary definition, triggering the notification.
When prompted to redefine the block, type Y (Yes) and press .
When you insert a block from an external source, AutoCAD creates a link to that file. If you, or a teammate, opens that external source file and saves changes to it while you have the main drawing open, AutoCAD detects that the "host file" (the source) has been updated [1].
Ensure "Include blocks from external references" is checked if your host file uses XREFs. 3. Filter Blocks & Properties
| Do This ✅ | Avoid This ❌ | |-----------|---------------| | Store the host file on a fast, reliable server. | Save it on your local C: drive (others can’t reach it). | | Use a naming convention with versions (e.g., Blocks_v2.dwg ). | Overwrite the host file while users are actively inserting from it. | | Run AUDIT and PURGE on the host file weekly. | Define blocks with the same name as standard AutoCAD blocks (e.g., Table ). | | Notify the team via chat/email when you update. | Assume AutoCAD will automatically "see" the changes—it won't. |
Look for any files displaying a yellow warning exclamation mark. Right-click the flagged file. Click to refresh the host file data. Best Practices to Prevent Block Errors
When you update a block inside Central_Blocks.dwg and save it, users who re-insert from that same host file will get the updated definition—provided they force a reload.
A quick search on Reddit or the Autodesk Forums reveals many users asking: "Is 'AutoCAD Block Host File Updated' a virus?"
Select or Clear Cache , then select Always keep on this device . Restart AutoCAD and reopen your host file. 4. Check External References (Xrefs)
