You must paste intermediate certificate/chain Ordering while Comodo Certificate without CA Bundle. Read to learn more.

If you order a Comodo Certificate sometimes instead of sending the CA Bundle in a single file, they'll send multiple files. You need to paste these into the intermediate certificate/chain in this order:

• COMODORSADomainValidationSecureServerCA.crt
• COMODORSAAddTrustCA.crt
• AddTrustExternalCARoot.crt

These should be pasted one after the other (including the header/footer in each file) into the intermediate certificate/chain for all browsers to accept the certificate properly.

Note that if Comodo send you a CABundle file, that contains this all put together for you.