Security News > 2023 > March > Microsoft shares fix for Outlook login errors in Exchange environments
Microsoft has shared a fix for Outlook sign-in errors that iOS and Android users may encounter with mailboxes in some Exchange environments.
"The error occurs in a hybrid Exchange environment, for mailboxes in on-premises Microsoft Exchange Server or Exchange Online," the company said in a support document released on Tuesday.
According to Redmond, the likely cause is a missing Exchange ActiveSync access rule that would allow users using Outlook iOS and Android apps to connect to the Exchange Online server.
To resolve these connectivity problems, admins must ensure that hybrid Modern Auth is toggled on and add a new Exchange Online access rule for mobile Outlook apps.
Last year, Microsoft also provided a workaround for a separate and ongoing known issue causing sign-in issues for some Outlook for Microsoft 365 customers and blocking them from accessing their accounts.
The company also rolled out a fix for another issue known since August that was causing Outlook for Microsoft 365 to freeze and crash after launch.
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