Message type: E = Error
Message class:  CNV20201 -  
Message number: 320
Message text: Ext. NoRg: Obj. &1,No. &2,to-year &3,source subobj. &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 CNV20201320 typically relates to issues encountered during data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or similar tools. This error message indicates that there is a problem with the external number range for a specific object and sub-object during the migration process.
Cause: The error message CNV20201320 can occur due to several reasons: Number Range Issues: The specified object and sub-object do not have a defined number range for the specified year. This can happen if the number range is not properly configured in the system. Data Inconsistencies: There may be inconsistencies in the data being migrated, such as missing or incorrect entries that do not align with the expected number range. Configuration Errors: The configuration settings for the number range might not be set up correctly in the target system.
Solution: To resolve the CNV20201320 error, you can take the following steps: Check Number Range Configuration: Go to the
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV20201319 No number range found for &1,subobj. &2!
What causes this issue?  The (document) number belongs to none of the number range intervals defined in table NRIV for number range object &V1&...
CNV20201318 Number level for &1, &2, &3, &4 initialized in CNV_20201_NRIV_O
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20201321 No number range found for &1,subobj. &2,fiscal year &3!
What causes this issue?  The (document) number belongs to none of the number range intervals defined in table NRIV for number range object &V1&...
CNV20201322 Another &1 numbers without number range for subobj. &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.