While testing Openfire 4.5.1 with a rather large set of Openfire plugins, we hit the situation that an ConcurrentModificationException occurred in the loading process of the plugins. The direct result is some corruption in the server state, which blocks the loading of other plugins and the server not responding. Restarting does not help either.
The exception is thrown when in line org.jivesoftware.openfire.container.PluginManager:379 the pluginsLoaded map is looped in order to get a an entry.
It is easy to imagine this should happen: the plugins are loaded simultaneously, using a unsynchronised map to add and retrieve data from it. The question is why nobody has reported this problem before.