Message type: E = Error
Message class:  EU - Development Environment 
Message number: 146
Message text: A message number may only contain digits
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 EU146 ("A message number may only contain digits") typically occurs when there is an issue with the format of a message number in the SAP system. This error is often encountered in the context of message classes and message numbers, particularly when defining or using custom messages in ABAP programs or when working with message handling in SAP.
Cause:
The error is caused by the following scenarios:
Invalid Message Number Format: The message number provided contains non-numeric characters (e.g., letters, special characters).
Incorrect Configuration: There may be a misconfiguration in the message class or the way messages are being referenced in the code.
Typographical Error: A simple typo in the message number can lead to this error.
Solution:
To resolve the EU146 error, you can take the following steps:
Check Message Number: Ensure that the message number you are using consists only of digits (0-9). For example, valid message numbers are 000, 001, 002, Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
EU145 Navigation terminated
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
EU144 You can only rename & in logical database maintenance
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
EU147 Unable to generate for program type &
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
EU148 Generation executed
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.