Converting cer (with csr and key) to pfx

Question

¿I can make a PFX certificate from cer, csr and key files?

Actually I have this files

• ceti.cer
• ceti.csr
• ceti.key

Answer 1

This command helped me:

openssl pkcs12 -export -out user.pfx -inkey user.key -in user.cer -certfile rootca.crt

the responses above returned an error "Unable to load certificates".