Message type: E = Error
Message class:  SLMP_RT - SL Protocol Runtime Message Class 
Message number: 254
Message text: Field &1 of entity &2 has wrong type (Exp: &3 Act: &4)
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 SLMP_RT254 indicates that there is a type mismatch for a field in a specific entity. This error typically occurs when the data type of a field in the input does not match the expected data type defined in the system for that field.
Cause: Data Type Mismatch: The field &1 of entity &2 is expected to have a certain data type (e.g., integer, string, date), but the actual data provided (indicated by &4) does not match the expected type (indicated by &3). Incorrect Mapping: If you are using an interface or data mapping, the mapping might be incorrect, leading to the wrong data type being sent.
Configuration Issues: There may be issues in the configuration of the entity or field definitions in the SAP system.
Solution: Check Data Types: Verify the expected data type for the field &1 in entity &2. Ensure that the data being sent matches this expected type. Data
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
SLMP_RT253 Implemented field &1 is not the key of entity &2
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SLMP_RT252 Model field &1 of entity &2 not implemented
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SLMP_RT255 Field &1 of entity &2 has wrong link (Exp: &3 Act: &4)
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
SLMP_RT256 DC_SET &1 uses wrong structure (Exp: &2 Act: &3)
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.