2809250 - Error Message Grouping XXXX has external number assignment, enter a number encountered in Supplier Migration

While performing the migration for supplier below error occurs:

"Grouping xxxx has external number assignment, enter a number"

"Image/data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental."

SAP S/4HANA.

R1091, migrate your data, supplier, Grouping xxxx has external number assignment, enter a number, The business partner needs a key to identify it, This key was not specified, supplier migration, LTMC, migration cockpit, migration template, S/4HANA cloud, S4_PC, CA-GTF-MIG, external grouping, internal grouping, BP, external number assignment. , KBA , CA-GTF-MIG , SAP S/4HANA Data Migration Cockpit Content , LO-MD-BP , Business Partners , Problem