The way I upgraded to 7.4 was as follows.

First make sure that /etc/yum/vars contains the files releasever and slreleasever.  The former should have the major version number, i.e., 7:

# cat /etc/yum/vars/releasever 
7

The later may have the latest minor version, e.g.:

# cat /etc/yum/vars/slreleasever 
7.3

Edit /etc/yum/vars/slreleasever and change it to 7.4:

# cat /etc/yum/vars/slreleasever 
7.4

If you want to have always the latest version then replace 7.4 with 7x above:

# cat /etc/yum/vars/slreleasever 
7x

Then you can do the usual upgrade:

# yum clean all

# yum update

etc.

Then check that the upgrade was sucessful:

# cat /etc/redhat-release 
Scientific Linux release 7.4 (Nitrogen)

That worked for me.


-  Miguel A. Lerma
  
________________________________________
From: [log in to unmask] <[log in to unmask]> on behalf of Mark Stodola <[log in to unmask]>
Sent: Tuesday, November 28, 2017 7:44 AM
To: [log in to unmask]
Subject: Re: Upgrading to SL 7.4 not working

On 11/27/2017 09:51 PM, stephen sefick wrote:
> Hello,
>
> I have yum-conf-7x installed, but I am unable to upgrade to 7.4. I can
> provide anything that may be needed to help. I could change all of the
> repos to point to 7.4, but I feel like there is a better way to this
> than that.
>
> kindest regards,
>
> Stephen Sefick, PhD

Any more detailed would be helpful.  What command are you running to
upgrade, what is the output/error you are getting, etc?  Just to
clarify, it is yum-conf-sl7x, correct?