I am new to linux (using lubuntu 18.04) so I could easily be doing something wrong, but I've searched for a few days and I can't find anything that already exists and looks like my problem.
I've tried updating my certificates and I disabled my firewall just to be sure that isn't blocking forge. I should be using Java 8. I don't know what else to try from here.
I've uploaded my installer log. Thank you
forge-1.12.2-14.23.4.2705-installer.jar.log
Edit: I found a solution on stack overflow -
# Ubuntu 18.04 and various Docker images such as openjdk:9-jdk throw exceptions when
# Java applications use SSL and HTTPS, because Java 9 changed a file format, if you
# create that file from scratch, like Debian / Ubuntu do.
#
# Before applying, run your application with the Java command line parameter
# java -Djavax.net.ssl.trustStorePassword=changeit ...
# to verify that this workaround is relevant to your particular issue.
To clarify, I was getting an SSL exception that was caused by the way ubuntu installs java? I'm not sure, but it's fixed anyway.