iOS 11.3 and 11.4 issues (network connection lost)

If your users are experiencing issues on iOS 11.3.x and iOS 11.4.x during MFA flows, make sure to update to the latest ADAL 2.6.3 (https://github.com/AzureAD/azure-activedirectory-library-for-objc/releases/tag/2.6.3)

Specifically, you might notice an increase in ADAL failures with NSURLErrorDomain and error code -1005 (network connection lost). The reason for that is the change introduced in iOS 11.3 around handling of network requests when application is backgrounded. Previously, iOS would close network connection only when device gets locked. After iOS 11.3 it's now dropping network connections immediately when application is backgrounded. However, it becomes an issue only for webpages that make POST requests to check MFA completion, because iOS automatically retries idempotent network requests. Therefore, you might notice it only for some of your users. See more details here: https://developer.apple.com/library/content/qa/qa1941/_index.html