( To resolve this cleanly in Odoo (v16, v17, or v18).

Step 1: Check Warehouse Routes & Rules

1. Go to Inventory → Configuration → Warehouses.
2. Open your warehouse.
3. Change the Outgoing Shipment strategy to "Ship directly from stock (Ship Only)".

Then, go to:

• Inventory → Configuration → Routes
• Search for routes with names like:
  • Make To Order
  • Your Warehouse: Delivery
  • Or custom routes that mention MTO, Ship, or Pick

For each route involved in shipping or MTO:

1. Open it and go to the Rules tab.
2. Ensure each rule has:
   • A valid source and destination location.
   • A defined action (e.g., Pull From, Push To).
   • Correct picking type (check Operation Type).

If _get_mto_pull_rule fails, it's usually because no rule with procure_method = make_to_order and location_src_id for the warehouse is found.

Step 2: Check Product Routes

1. Go to Inventory → Products → Products.
2. Choose a product that was involved in the failed delivery order.
3. Under the Inventory tab, check if:
   • Routes contains "Make To Order" or custom MTO routes.
   • If yes, but you’ve now changed the warehouse to use “Ship Only”, either:
     • Uncheck Make To Order on the product, OR
     • Make sure a valid MTO pull rule exists for the warehouse.

Step 3: Fix or Reset the MTO Pull Rule

1. Go to Inventory → Configuration → Routes.
2. Find the Make To Order route (usually internal).
3. Open its Rules.
4. Make sure at least one rule is present with:
   • Procurement Method = Make To Order
   • Source Location = the Stock location of your warehouse
   • Destination Location = based on the process (could be customer or transit)
   • Operation Type = Delivery Order
   • If not present — create it manually.

Step 4: Developer Mode — Check Default Rule Logic

• Sometimes when changing the warehouse configuration, the old rules are left but the warehouse expects different default pull/push logic.
• You can go to Technical → Rules and clean up old pull/push rules that are no longer valid.

Step 5 : Restart Server & Upgrade Stock Module .

Thanks & Regards , 

Company :- DataInteger Consultancy Services LLP