Symptoms

Attaching a screenshot to an Issue on JIRA versions older than 5.1.3 may close the window and throw a null pointer exception.

• No error messages are displayed to the user.
• The window will close (as expected)
• No attachment is added to the issue.
• No comment is added to the issue.
• No activity is added to the issue.

Cause

The "Whoslookin" plugin on version 2.0 causes this problem. When disabling the plugin, attaching a screenshot will work as expected. T "

plugin: whoslooking
Version: 2.0
Developer: Atlassian
Plugin Key: com.atlassian.jira.plugins.whoslooking

Resolution

Upgrade to the latest version of the plugin and upgrade JIRA to any version between 5.0.7 and 5.1.3 which is the latest version supported for this plugin. 

Please check the Who's Looking plugin page to check for updates.