Message type: E = Error
Message class:  CNV_20700 - Material number conversion 
Message number: 221
Message text: No structure maintained for Object ID &1 in field OBJECTSTRU
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_20700221 indicates that there is no structure maintained for a specific Object ID in the field OBJECTSTRU. This error typically arises during data migration or conversion processes, particularly when using SAP's data migration tools or during system upgrades.
Cause: Missing Structure Definition: The Object ID referenced in the error does not have a corresponding structure defined in the system. This could be due to a configuration oversight or an incomplete setup during the migration process. Incorrect Object ID: The Object ID being referenced may be incorrect or not valid in the context of the operation being performed. Data Migration Tool Issues: If you are using a specific data migration tool or program, it may not have been properly configured to recognize the Object ID.
Solution: Check Object ID: Verify that the Object ID mentioned in the error message is correct and exists in the system. You can do this by checking the
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_20700220 For Details, check log of sub-activity 'CNV_10940_ANALYSIS_MAIN_XXXX'
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_20700219 Conversion is based on the mapping table with NCE
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_20700222 No structure maintained for Object ID &1 in field SUBOBJSTRU
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_20700223 No conversion relevant field for object id &1 and structure &2
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.