Message type: E = Error
Message class:  CNV_20100 - Messageclass for chart of account conversion 
Message number: 386
Message text: Country-specific CoA &1: Account &2 is not used as alternative account
Chart of accounts &V1& is only used as a country-specific chart of
accounts.
&V2& is an account in chart of accounts &V1& (SKA1-SAKNR).
&V2& is not used as an alternative account for any of the relevant
company codes (SKB1-ALTKT).
Warning.
Account &V1& &V2& is probably obsolete.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message CNV_20100386 indicates that there is an issue related to the Chart of Accounts (CoA) configuration in the context of a country-specific setup. Specifically, the error states that a certain account (denoted as &2) is not being used as an alternative account for the specified Chart of Accounts (denoted as &1).
Cause: Missing Alternative Account Configuration: The account specified in the error message is not set up as an alternative account in the system for the given Chart of Accounts. Incorrect Mapping: There may be a mapping issue where the account is expected to be an alternative account but is not correctly configured in the system. Data Migration Issues: If this error arises during a data migration process, it could be due to missing or incorrect data in the migration files.
Solution: Check Account Configuration: Go to the transaction code OBY6 (or the relevant configuration transaction) to check the settings for the Chart of
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_20100385 &1: in CNVTABLES sequence number was set to value &2
What causes this issue?  Table &V3& must be processed before table &V1&.System Response  To ensure this, the sequence number for table...
CNV_20100384 Set class is initial; set values are converted as cost elements
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_20100387 No organizational unit; &1=&2 is converted independent of org. unit
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_20100388 Table &1 is converted before table &2
What causes this issue?  You want to implement a country-specific chart of accounts. This means that the previously operative chart of accounts is def...
Click on this link to search all SAP messages.