All sorts of things. Can't tell without more detail. This question is a bit like ringing up a car mechanic and saying "my car is broken" and not telling them where you are, whether it starts, whether you've dumped it in a ditch, or even if you're in the same country as the car...
What do you actually get when you try to log in? Screens? What version are you running? Browser? What else have you tried? As Jobin says, most importantly what do the logs say?
Clearing the cache has allowed me to login again, but why? What could be cached on a brand new install so as to prevent me from logging in?
Difficult to say without more information. Did you have an old version installed (then uninstalled, to make way for the new one)? That could do it.
The logs are whereever you've chosen to put them. Look for catalina.out in the logs directory of your installation (assuming you're using Tomcat) and atlassian-jira.log under the install as well.
In the past, Portfolio for Jira required a high degree of detail–foresight that was unrealistic for many businesses to have–in order to produce a reliable long-term roadmap. We're tur...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs