The error message “No valid source of supply could be found” in SAP often occurs during procurement processes, such as purchase requisitions, purchase orders, or production orders. To resolve this error when using transaction codes (T-codes), follow these steps:

1. Check Material and Vendor Data:

• Ensure that the material and vendor data are correctly maintained in SAP. Check that the material master data and vendor master data are up-to-date.

1. Source Determination (ME51N, ME21N, etc.):

• When creating a purchase requisition (ME51N), purchase order (ME21N), or other procurement documents, make sure to select the correct source of supply (vendor, plant, or stock location). Double-check the input fields to avoid any typos.

1. Material Procurement Settings:

• Verify the procurement settings for the material, including the procurement type (e.g., make-to-stock, make-to-order, purchase-to-order) and the source list.

1. Source List (ME01):

• Use the transaction code ME01 to maintain the source list. Ensure that the material is assigned to the correct vendor or source of supply. Make any necessary adjustments if the source list is used in your procurement process.

1. Purchase Info Record (ME11):

• If you use purchase info records, create or update them using ME11 to establish the relationship between materials and vendors. Make sure they are maintained accurately.

1. Stock Availability:

• Check the stock availability in the relevant storage location. If there is insufficient stock, SAP may not find a valid source of supply.

1. Check for Customization:

• Review any customizations or specific business rules that might affect the source determination process. Ensure they are correctly configured.

1. Review Error Messages:

• Pay attention to any additional error messages or warnings provided by SAP during the transaction. They may offer more specific insights into the problem.

1. Authorization:

• Ensure that you have the necessary authorization to perform the procurement action. Lack of authorization can also lead to this error.

1. SAP Notes and Documentation:
   • Check SAP documentation and relevant SAP Notes for your specific SAP version and industry. There may be specific notes or recommendations addressing this error.

If you have followed these steps and are still encountering the error, consider involving your SAP system administrator or a consultant with expertise in SAP procurement processes. They can help troubleshoot and resolve the issue, especially if it involves complex configurations or customizations in your SAP system.