Message type: E = Error
Message class:  CNV20201 -  
Message number: 308
Message text: NRIV no. range lower than previous no.! NoRg. &1, subobj. &2, to-year &3
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 CNV20201308 indicates that there is an issue with the number range (NRIV) configuration in your SAP system. Specifically, the error states that the lower limit of a number range is less than a previously defined number range. This can occur during data migration or when setting up number ranges for certain objects.
Cause: The error is typically caused by one of the following: Incorrect Number Range Configuration: The number range you are trying to define has a lower limit that is less than the lower limit of an existing number range for the same object. Data Migration Issues: During data migration, if the system tries to assign a number that falls outside the defined range, this error can occur. Inconsistent Data: There may be inconsistencies in the data that are being migrated or processed, leading to conflicts in number range assignments.
Solution: To resolve this error, you can take the following steps: Check Number
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV20201307 Ext. number range &1,subobj. &2,to-year &3: max. no.= &4
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20201306 Ext. number range &1,subobj. &2: max. no.= &3
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20201309 __NRIV: No.range =&1, max. number in &2: &3
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20201310 Ext. and int. NoRg to be merged! Obj. &1,NoRg. &2,ref.subobj.&3
What causes this issue?  The indicated number range is defined as external in a subobject, while the same number range is defined as an internal numbe...
Click on this link to search all SAP messages.