Symptoms

The following appears in the atlassian-confluence.log:

ERROR [DefaultQuartzScheduler_Worker-3] [confluence.plugin.webresource.ConfluenceWebResourceIntegration] 
getRelativeBaseUrl No non-null relative base URL found

Cause

This error is nothing to worry about. It is thrown by a Confluence cron job, which is likely to be the referralQueueTrigger that checks for external referral links or DailyReportJob that run Email Daily Reports. By default this job runs every 15 seconds. To determine which job is causing the error, you can view Confluence Admin > Scheduled Jobs and cross-checked the time that error occurred in the logs with the time that the cron job is running. Regardless, the error can be safely ignored. However, this error is misleading and since it is harmless, Confluence should not be throwing it. The bug is tracked here:  CONF-27011 - Getting issue details... STATUS