Open the Storage-object UC_ECC_PLUGINS for editing
Find the line for the RA Solution you are trying to load. For each loaded RA solution, there is a line ECC-AE-SHEET-name where the name is the RA solution. I.e. for RA FTP it is ECC-AE-SHEET-RA-FTP
Stop the corresponding RA Agent(s)
Delete the line for the solution to load from the Storage-Object UC_ECC_PLUGINS. I.e. for RA-FTP the line with ECC-AE-SHEET-RA-FTP