You tried to rename a group or field in the TIBCO metadata tree. However, a column in the source or target definition already contains the group or field in its map value. For example, the TIBCO metadata tree contains the group GROUP1. GROUP1 contains a field FIELD1. FIELD1 is already a column in the source definition. In the metadata tree, you want to change the name of GROUP1 to GROUP2. Because FIELD1 is already a column in the source definition, the change is not allowed.