We upgraded to 3.6.1 recently and now we are having problems when creating links to issues. I have checked all the permissions, they are all good. I can create a link to an issue, it will show up in the issue where I created it from as long as there is no other links there. As soon as I get more than one link, the links and attachments are no longer visible. This is the error in the log: SEVERE: METHOD: "showIssueDetails", exception: java.lang.ClassCastException at com.atlassian.jira.issue.comparator.IssueKeyComparator.compare(IssueKeyComparator.java:18) at org.apache.commons.collections.comparators.ComparatorChain.compare(ComparatorChain.java:277) The problem is that IssueKeyComparator is expecting a Issue object for certain compare's and GenericValues for others. The attached recompiled class file contains a fix. The code below replaces the code in the 'compare' routine: String key1 = null; String key2 = null; if (o1 == null && o2 == null) return 0; else if (o2 == null) // any value is greater than null return 1; else if (o1 == null) // null is less than any value return -1; if(o1 instanceof GenericValue && o2 instanceof GenericValue) { key1 = ((GenericValue ) o1).getString("key"); key2 = ((GenericValue ) o2).getString("key"); } else if(o1 instanceof Issue && o2 instanceof Issue) { key1 = ((Issue ) o1).getKey(); key2 = ((Issue ) o2).getKey(); } return KeyComparator.COMPARATOR.compare(key1, key2);