VSTS Agent cannot overwrite nor remove the DLL when used by IIS

Question

VSTS agent for AZure devOPS is not able to remove or overwrite the file when a URL has been invoked . However when the IIS worker process is killed and the Release is redeployed it is working fine .

I have enabled both overwrite and clean option . But it is still unable to deploy.

2018-11-17T13:05:23.2176452Z ##[section]Starting: Copy Files to: D:\IIS Hosting\CICD
2018-11-17T13:05:23.2179160Z ==============================================================================
2018-11-17T13:05:23.2179236Z Task         : Copy Files
2018-11-17T13:05:23.2179314Z Description  : Copy files from source folder to target folder using match patterns (The match patterns will only match file paths, not folder paths)
2018-11-17T13:05:23.2179373Z Version      : 2.117.2
2018-11-17T13:05:23.2179438Z Author       : Microsoft Corporation
2018-11-17T13:05:23.2179495Z Help         : [More Information](https://go.microsoft.com/fwlink/?LinkID=708389)
2018-11-17T13:05:23.2179554Z ==============================================================================
2018-11-17T13:05:23.4602460Z found 7 files
2018-11-17T13:05:23.4602904Z Cleaning target folder: D:\IIS Hosting\CICD
2018-11-17T13:05:23.4650798Z ##[error]Unhandled: Failed rmRF: EPERM: operation not permitted, unlink 'D:\IIS Hosting\CICD\AZSync.Web.dll'
2018-11-17T13:05:23.4659907Z ##[section]Finishing: Copy Files to: D:\IIS Hosting\CICD

Gives an error -

Answer 1

The solution was to have a task to copy app_offline.htm to the IIS hosting directory which would stop dotnet core from running . Copy/ overwrite all files and then remove app_offline.htmusing a delete file task.