As of the April 2026 update, Microsoft has added new warnings for unsigned RDP files. Here are a few ways to work around this so the connecting user receives no errors. Note that the host is unaffected, it is only the client (remote end) that needs updating.
Via RMM/command line:
reg add "HKLM\SOFTWARE\Microsoft\Terminal Server Client" /v RdpLaunchConsentAccepted /t REG_DWORD /d 1
reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\Client" /v RedirectionWarningDialogVersion /t REG_DWORD /d 1
Use the attached .reg file or implement these changes via Group Policy.
Attached files: