Message type: E = Error
Message class:  PPC1VA - Messages for Variance Dialog for DI Backflush 
Message number: 003
Message text: Enter a material number
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 PPC1VA003 ("Enter a material number") typically occurs in the context of production planning or related modules when the system expects a material number to be entered, but it is missing or invalid. This error can arise in various transactions, such as creating production orders, planning, or inventory management.
Cause:
Missing Input: The user did not enter a material number in the required field.
Invalid Material Number: The material number entered does not exist in the system or is not valid for the current context (e.g., it may be inactive or not assigned to the plant).
Field Configuration: The field for the material number may be set as mandatory in the configuration, and the user did not provide a value.
Authorization Issues: The user may not have the necessary authorizations to view or use the material number.
Solution:
Enter a Valid Material Number: Ensure that you input a valid material number in the required Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
PPC1VA002 Production version &1 does not exist for material &2 in plant &3
What causes this issue?  The production version &V1& of material &V2& does not exist in plant &V3& or this production version ...
PPC1VA001 Material &1 does not exist in plant &2
What causes this issue?  Material &V1& does not exist in plant &V2&.System Response  The system issues an error message and will not a...
PPC1VA004 Enter a plant
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
PPC1VA005 No error exists for line selected. Not possible to display error
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.