Q: IIS 8.5 Enhanced logging not working when adding custom field I have Windows Server 2012 R2 Standard with IIS 8.5.
I added the enhanced logging custom filed for our website (on site level): X-FORWARDED-FOR
as described in: https://www.iis.net/learn/get-started/whats-new-in-iis-85/enhanced-logging-for-iis85
When I click Apply the site stops logging completely. No errors are visible in the Application Event log.
After I remove the custom field the login resumes.
I need this to capture to original client IP from Cloudflare. 
Please help! 

A: I've encountered something similar to IIS logging that stopped after awhile. It turns out to be a Windows Server 2012 R2 bug under "KB 2982169 W3C logging service crashes in IIS 8.5 on a server in Windows 8.1 or Windows Server 2012 R2"
The issue was resolved after installing https://support.microsoft.com/en-us/help/3013769/december-2014-update-rollup-for-windows-rt-8.1,-windows-8.1,-and-windows-server-2012-r2. 
There're also a bunch of other updates which you may find useful here: https://support.microsoft.com/en-us/help/24717/windows-8-1-windows-server-2012-r2-update-history.
