When configuring SEPM to enable or update the LPS Custom PAC file [1], the error "Symantec Endpoint Protection cannot validate the custom PAC file. Try a different file" is shown.
[1] Bypass Endpoint Protection Web Traffic Redirection using a custom PAC file
Under investigations
SEPM versions 14.3, 14.3 MP1 and 14.3 RU1
Run the SEPM console as administrator
Broadcom engineering looking into issue.