webapi helppage debug works and on iis No documentation available

if your helpage works great when debugging, but after publishing the api to the disk and browse it, it doesn't work,

that may because the help page document isn't be published

the xml document for help page description is YourProjectName.XML

can see http://stackoverflow.com/a/14843682/4573839

or https://coderwall.com/p/sqmrog/3-easy-steps-to-create-webapi-documentations

you can know the document's filename and location in your project.

Then, I found that the place where webapi  read the document is at HelpPageConfig.cs in the project

http://i.imgur.com/3P2WhB3.png

and it use the path : HttpContext.Current.Server.MapPath("YourDocumentName.XML")

it's the path directly under your IIS Site physical Folder

so, just copy the document.xml from your project folder to the IIS site folder,

and the help page will work

also can see 

asp.net webapi publish - xml files not copy

http://stackoverflow.com/a/34777811/4573839