Following a recent update to the Google Chrome Browser, in my case to version 42.0.2311.90 I was unable to select the ‘Use Windows Session Authentication’ option when authenticating the vSphere Web Client.
In order to resolve this issue I was required to enable the use of NPAPI plug-ins to support has been disabled by default in versions 42.0 and above, as per https://www.chromium.org/developers/npapi-deprecation.
To workaround the issue you can perform the following:
1) From the address bar, browse to ‘chrome://flags/#enable-npap’.
2) Search for ‘Enable NPAPI Mac, Windows’ and select ‘Enable’.
3) Relaunch the browser.
It is useful to note that from versions 45 and above the above workaround will not be available, the current version of the vSphere Web Client that was impacted in this instance was Version 5.5.0 Build 2026576.
In September 2015 (Chrome 45) we will remove the override and NPAPI support will be permanently removed from Chrome. Installed extensions that require NPAPI plugins will no longer be able to load those plugins.