Since the stack trace you posted seems to be related to "com.atlassian.confluence.plugin.descriptor.web.ConfluenceWebInterfaceManager" I also recommend clearing the plugins cache: How to clear Confluence plugins cache
Since the stack trace you posted seems to be related to "com.atlassian.confluence.plugin.descriptor.web.ConfluenceWebInterfaceManager" I also recommend clearing the plugins cache: How to clear Confluence plugins cache