IncompatibleClassChangeError when Accessing a Thumbnail Image Due to JDK

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Symptoms

Users are getting a JPEGImageEncoder exception uploading a user icon.

java.lang.IncompatibleClassChangeError: Found class com.sun.image.codec.jpeg.JPEGImageEncoder, but interface was expected
at com.atlassian.core.util.thumbnail.Thumber.storeThumbImage(Thumber.java:265)
at com.atlassian.core.util.thumbnail.Thumber.createThumbnail(Thumber.java:175)
at com.atlassian.core.util.thumbnail.Thumber.retrieveOrCreateThumbNail(Thumber.java:131)
at com.atlassian.confluence.pages.thumbnail.DefaultThumbnailManager.getThumbnail(DefaultThumbnailManager.java:75)

Cause

An unsupported Java version is being used such as OpenJDK that has a different class definition.

Resolution

  1. Download a supported Oracle Java version.
  2. Configure Confluence to use the standard JDK.

Last modified on Mar 30, 2016

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