2132333 - Source system cannot use any of the proposed connection names

When trying to create a new source system connection in transaction RSA1 the following popup appears:

The RFC connection is pointing to the correct source system and there  is no such entry available in table RSBASIDOC in your source system.

For both options: 'DELETE' and 'Do Not DELETE' you are getting the error:

SAP NetWeaver

Business Warehouse, BW, RSAR362, RSA1 "is already know" "in the source system", RSAR502 , KBA , BW-WHM-DST-SRC , Source Systems , Problem