https://userapps.support.sap.com/sap/support/knowledge/en/2106812
2106812 - Error Function module /1CRMGC/BUPA_MAIN_FIL does not exist for the object customer_main |...
When setting up initial load of object BUPA_MAIN from ERP TO CRM you recrecive the error when saving the filter in R3AC1.