When running Web Agent, when user accesses a site protected with
Windows Authentication Scheme, if the browser is used in Private Mode
(Incognito), then the browser receives a popup.
At first glance, this is a browser issue, and depending the browser
version, there are parameters to activate to have Windows
Authentication working on Firefox (1), Chrome (2) and Edge (3).
(1)
How to enable SSO when using private mode in Firefox?
Actually you can enable the SSO in Firefox private mode by setting
"network.auth.private-browsing-sso" to true (along with the regular
settings you do in normal mode).
https://superuser.com/questions/1374835/how-to-enable-sso-when-using-private-mode-in-firefox
(2)
SSO is not working Chrome Incognito in Version 81.0.4044.92
Open chrome, in address bar open: chrome://flags/ and at search option
for flag, search for “Enable Ambient Authentication in Incognito mode”
flag and change it from ‘Default’ to ‘Enabled’. Then ‘relaunch’ the
chrome. This resolved the credential pop-up issue for Chrome.
https://support.google.com/chrome/thread/38855209/sso-is-not-working-chrome-incognito-in-version-81-0-4044-92?hl=en
(3)
Ambient Authentication has been added to Edge for InPrivate and Guest sessions
Enable Ambient Authentication in InPrivate mode
Enables ambient authentication in InPrivate mode. This flag may be
overriden by policies. – Mac, Windows
#enable-ambient-authentication-in-incognitoEnabled
In Edge76, Edge18, and Firefox, running the browser in InPrivate
mode disables automatic Integrated Windows Authentication.
https://techcommunity.microsoft.com/t5/discussions/ambient-authentication-has-been-added-to-edge-for-inprivate-and/m-p/1205120