case conf.AccessKey == "" && conf.SecretKey != "" || conf.AccessKey != "" && conf.SecretKey == "":
		return nil, errors.New("both the access and secret keys are required")
	case conf.AWSRole && (conf.AWSRoleWebIdentityTokenFile != "" || conf.AWSRoleARN != "" || conf.AccessKey != "" || conf.SecretKey != ""):
		return nil, errors.New("AWS Role cannot be activated with static credentials or the web identity token file")

	tierType, exists := config.isTierNameInUse(tierName)
	if !exists {
		return errTierNotFound
	}

	cfg := config.Tiers[tierName]
	switch tierType {
	case madmin.S3:
		if creds.AWSRole {
			cfg.S3.AWSRole = true
		}
		if creds.AWSRoleWebIdentityTokenFile != "" && creds.AWSRoleARN != "" {
			cfg.S3.AWSRoleARN = creds.AWSRoleARN
			cfg.S3.AWSRoleWebIdentityTokenFile = creds.AWSRoleWebIdentityTokenFile
		}