Eric,
Sorry that you are seeing this problem.
1. Are you behind a firewall or proxy?
2. Can you please check if you can download the said jar to your machine without any problem? : http://updates-cdn.genuitec.com/codemix/updates/cm20190619b/plugins/com.genuitec.eclipse.code_3.2.0.201906181919.jar
3. Go to Preferences > Install/Update > Available Software Sites, and look for the CodeMix site there. Select it and hit “Reload”. Now restart Eclipse and try to install again from Help > Check for Updates, there could be a corrupt cache that this should fix.
4. If the above suggestion does not work, then as an alternative, you can paste the file you downloaded into your Eclipse installation’s plugins (you’ll see a number of other jar files there). Now start Eclipse, and attempt the installation again from Help > Check for Updates, it should now skip downloading this file.
Apologies for inconvenience caused. Please let us know how you get on with it.
–Swapna
Genuitec Support