Symptoms

When an image is resized in Confluence edit mode, the image breaks:

The following appears in the atlassian-confluence.log:

2014-04-24 10:29:43,084 ERROR [main] [atlassian.confluence.security.DefaultCaptchaManager] afterPropertiesSet Could not initialise CAPTCHA service. The most likely reason for this is that Java's graphics subsystem is not properly configured. Try starting Confluence's JVM with the -Djava.awt.headless=true option. no awt in java.library.path
java.lang.UnsatisfiedLinkError: no awt in java.library.path

Cause

The Java graphical library is corrupted, which breaks the image resize feature in Confluence.

Resolution

1. Shutdown Confluence.
2. Upgrade Java to the latest supported version.

3. Set your environment variable to the new version of Java, as documented in Installing Java for Confluence.

4. After you set the new version of Java as your environmental variable, follow the Configuring System Properties guide in case you're starting Confluence as a Windows service.
5. In step 5, after you click on the Java tab, tick the check box "Use default":
   
6. Click OK.

7. Start Confluence.

   Be sure to confirm that your Confluence instance is using the new Java version, at Confluence Admin > System Information