Login problem for IM web and Control Edge

Based on the following Notification from Microsoft:

Warning

Windows updates for CVE-2026-20833 enforce RC4 hardening in phases. Plan and complete remediation before full enforcement:

• January 13, 2026 - Initial deployment phase:Updates introduce audit signals and preparation controls.
• April 2026 - Enforcement phase (manual rollback available):Default Kerberos KDC behavior shifts to AES-first, and RC4-dependent scenarios can start failing unless explicitly configured.
• July 2026 - Enforcement phase (final):Updates remove rollback support and keep enforcement enabled.

we disabled the Kerberos RC4 encryption on the EntraID Domain Services.
The configuration was leading to the mentioned incident.

As this will be anyhow eminent to happen ( enforcement of Kerberos to AES ) we will continue internal investigation with Microsoft Support to identify root cause of the action applied today.
Until further notice the Kerberos RC4 encryption will remain enabled.