Microsoft Edge Enterprise — Intermittent Blue Coat Proxy Authentication Prompt
Product: Microsoft Edge for Business / Microsoft Edge Enterprise Component: Proxy authentication, HTTP networking and integrated authentication Operating system: Windows 11 Enterprise Proxy: Blue Coat / Broadcom forward proxy, port 8080 Proxy authentication configuration: Basic Auth/ IWARealm exact authentication method to be confirmed Affected browser: Microsoft Edge for Business Comparison browser: Mozilla Firefox, where the same behaviour has not been observed Impact: Intermittent interruption of browsing and loss of access to existing tabs until the user reauthenticates We are experiencing intermittent, unexpected proxy authentication prompts in Microsoft Edge for Business. The dialog states: Sign in to access this site. The proxy http://[bluecoat-host-url]:8080 requires a username and password. Your connection to this site is not secure. The prompt appears sporadically, sometimes while the browser is idle or while tabs displaying otherwise idle ServiceNow, deepl etc. pages cannot be accessed until user reauthenticates with autofill if proxy password is saved in order to be able to access those sites again. No explicit navigation or user interaction is necessarily taking place when the dialog appears. This behaviour was not observed previously and has become noticeable more recently especially since the migration of a lot of our workloads to the microsoft cloud. Firefox does not appear to exhibit the same symptom under comparable. We suspect that a background request, a new or reused proxy connection, proxy-session reauthentication, or an incomplete integrated-authentication exchange may be triggering the prompt. However, we have not yet identified the exact request or established whether the root cause is Edge, the proxy configuration, PAC routing, or the authentication infrastructure. usage conditions. Edge should silently authenticate to the configured enterprise proxy through the organisation's approved authentication mechanism, without unexpectedly displaying a credential prompt during normal browsing or background activity.
