Some exceptions are logged with logger.error("bla-bla"+e) instead of logger.error("bla-bla",e): I ran a simple search for all usages for Category.error(Object o), and found several occasions where the exception is logged as a string instead of a proper exception. This means that if the exception occurs, no stracktrace will be printed, which makes it difficult to track problems.

In other places, no logging was done at all. See

/confluence/src/java/com/atlassian/confluence/upgrade/MailDatabaseUpgradeTask.java

for example. In case of an error, the code should report that, not silently swallow the exception

We have to go through the code and find and fix as many of these problems, since they will come and haunt us at some point.