I'm trying to install apps onto our shiny new Splunk server, but when I try to install apps through the GUI, and I'm prompted with the Splunk.com login - I simply get an error message that says the login is invalid. I know this is not the case, because a coworker was able to confirm precisely the same thing: the login works on Splunk.com, but not in our Splunk Enterprise server.
I multitail'd all of the logs in $SPLUNK_HOME/var/log/splunk/ and the only one that moves when re-submitting the login form is the audit.log, which doesn't contain any information about the error.
Additionally, I've searched this site and only found one other question that was similar, to which the answer was "Install by file" which is apparently due to a "known issue in Windows". Our Splunk server is running on Ubunutu 16.04.