Message type: E = Error
Message class:  SEPMRA_SALESORDER - EPM Fiori Ref Apps: Messages for Sales Order 
Message number: 003
Message text: Payment term &1 does not exist
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message SEPMRA_SALESORDER003, which states "Payment term &1 does not exist," typically occurs when a sales order is being processed and the specified payment term is not recognized by the system. Here’s a breakdown of the cause, potential solutions, and related information:
Cause: Non-Existent Payment Term: The payment term specified in the sales order does not exist in the system. This could be due to a typo or because the payment term has not been defined in the configuration. Incorrect Configuration: The payment term may not be properly configured in the system, or it may have been deactivated or deleted. Master Data Issues: The customer master data may reference a payment term that is not valid or has been removed.
Solution: Check Payment Term: Go to the transaction code OVAK (or use the menu path: SPRO > Financial Accounting > Accounts Receivable and Accounts Payable > Business Transactions > Incoming Payments > Define Payment Terms). Verify
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
SEPMRA_SALESORDER002 Payment method &1 does not exist
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SEPMRA_SALESORDER001 Customer &1 does not exist
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SEPMRA_SALESORDER004 Ship-to party &1 does not exist
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SEPMRA_SALESORDER005 Bill-to party &1 does not exist
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.