Confluence is throwing blank page once in a while.

[AJITH PG]

Hello,

We are running confluence 5.9.11. Once in a while we are getting a blank page while accessing the site. I could see the following errors in the logs.

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2017-08-25 15:53:36,554 ERROR [ajp-nio-8009-exec-192 url:/rest/calendar-services/1...oming.json username:xxxx ] [extra.calendar3.rest.CalendarResource] getSubCalendars Unable to get events for subCa
lendarId: 146d3e2b-939d-4377-9bf5-e454f543175c
2017-08-25 15:53:36,768 ERROR [ajp-nio-8009-exec-192 url:/rest/calendar-services/1...oming.json username:xxxx ] [extra.calendar3.calendarstore.JiraCalendarDataStore] getSubCalendarContentInternal Th
e JQL query for project = "XXX" didn't return any results. Try changing the query.

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Could you please let me know what can be the cause for this? Also if it's something related to the performance issues, how can we get the information about what causing the issues? Let me know if any other details are needed from my end. 

Regards,

Ajith PG

[AnnWorley]

Hi Ajith,

For the cause of the Team Calendar error messages, it is usually invalid JQL or JQL pointing to JIRA content that the viewer doesn't have access to. We have a request open to change the log entries to be less alarming: As an administrator I would like invalid JQL to be logged as WARN or INFO rather than ERROR

Regarding the blank page being shown when you access Confluence, the most common cause of a blank page being displayed in the browser is accessing it on an invalid context path; please see: Getting a blank or white screen when accessing confluence via browser.

I look forward to hearing more about the performance issue if it doesn't turn out to be the context path after all.

Thanks,
Ann