Message type: E = Error
Message class:  CNV_MBT - PCL message class 
Message number: 435
Message text: The entered process step is not defined.Please enter a valid process step
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 CNV_MBT435 indicates that the process step you are trying to enter is not defined in the system. This error typically occurs in the context of data migration or conversion processes, particularly when using the SAP Migration Cockpit or similar tools.
Cause: Undefined Process Step: The process step you are trying to use has not been defined in the system. This could be due to a configuration issue or because the step is not part of the current migration project. Incorrect Input: The input provided for the process step may contain typographical errors or may not match the expected values. Missing Configuration: The necessary configuration for the migration project may not have been completed, leading to the absence of the required process steps.
Solution: Check Process Step Definition: Verify that the process step you are trying to enter is defined in the system. You can do this by checking the relevant configuration settings or
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_MBT434 Mass transfer ID 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...
CNV_MBT433 Package &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...
CNV_MBT436 Function module CNV_TDMS_SCR_DET_OBJS_FOR_CONV does not exist in system
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_MBT437 Some unexpected error occured in FM CNV_MBT_SCRAM_BLOCK_STAT_UPD
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.