The most common problem we see with JIRA authentication issues is when people use their Google or ActiveDirectory username, rather than their JIRA username. To use the JIRA API, you must use the JIRA username (which may not be the same as you use to log into JIRA). You can find your JIRA username in the JIRA UI on your Profile page (under your photo in the top right corner).
You may need to set the password associated with your JIRA username on the Profile page, too.
If your JIRA instance is integrated with ActiveDirectory, you may not see a link on your profile page to set your JIRA password. If there is no set password link, you can follow these instructions to set your password:
A 401 authentication error can also be caused when a user's Jira password expires. This can be verified by attempting to log in to Jira directly - If the password has expired the user will be prompted to change it. Updating the password within Jira and then updating the password used for the Jira integration within Aha! should resolve the authentication errors that are experienced.
A forced update to Atlassian accounts as of May 2017 has also caused some Aha! users to see 401 errors. You can read more about that change and potential workarounds here.