Message type: E = Error
Message class:  CNV_INDX - Messages for conversion of INDX-like tables 
Message number: 240
Message text: Action &1 is not allowed for error type &2 (RELID: &3, INDX key: &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 CNV_INDX240 typically occurs during data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or other data migration tools. This error indicates that a specific action is not permitted for a certain error type related to the index key.
Cause: The error message CNV_INDX240 can be triggered by several factors, including: Invalid Action: The action you are trying to perform (e.g., delete, update) is not allowed for the specified error type. Data Integrity Issues: There may be issues with the data integrity or consistency that prevent the action from being executed.
Configuration Issues: The configuration settings for the migration or conversion process may not allow the specified action for the given error type. Authorization Issues: The user executing the action may not have the necessary permissions to perform the action on the specified error type.
Solution: To resolve the CNV_INDX240 error, you can take the following steps: Check the Action: Verify that
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_INDX235 Structure &1 of component &2 of RELID &3 unknown
What causes this issue?  Component &V2& (RELID &V3&) has been marked for conversion. However, the structure of this component (&V1...
CNV_INDX234 Missing or wrong defn. of non-transp. field &1 (component &2 of RELID &3)
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_INDX241 For selected errors no common action is possible
What causes this issue?  For selected errors there is no common action that can be performed.System Response  The system issues an error message and w...
CNV_INDX245 INDX data check results not found for package &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.