Message type: E = Error
Message class:  USMD_MC - Messages for USMD Mass Change 
Message number: 001
Message text: Select at least one row.
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 USMD_MC001: "Select at least one row." typically occurs in the context of the SAP Master Data Governance (MDG) application, particularly when you are trying to perform an action that requires at least one selected item or row in a list or table. This error indicates that the system expects you to select at least one entry before proceeding with the operation.
Cause: No Selection Made: The most common cause of this error is that the user has not selected any rows in the list or table where the action is being attempted. User Interface Issue: Sometimes, the user interface may not be functioning correctly, leading to the inability to select rows. Authorization Issues: In some cases, the user may not have the necessary authorizations to select or modify the data, which can lead to confusion about whether rows are selectable.
Solution: Select a Row: Ensure that you select at least one row
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
USMD_MASS_LOAD053 Data for internal order &1 processed
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
USMD_MASS_LOAD052 Comp. code assignments for controlling area &1 profit center &2 processed
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
USMD_MC002 Select exactly one row.
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
USMD_MC003 An error occurred when processing method &1.
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.