Short description:<\/b> After the May 2026 Windows updates, many users started seeing \u201cUnverified source\u201d and certificate warnings during Remote Desktop connections. Here\u2019s what changed, why it happens, and how to fix it.<\/p>\n
In May 2026, Microsoft released new security updates for Windows and Remote Desktop services. Shortly after installing these updates, many users began seeing warnings such as \u201cThe identity of the remote computer cannot be verified\u201d or \u201cUntrusted certificate\u201d when connecting through RDP.<\/p>\n
The issue mainly affected companies using older Windows Server versions, self-signed certificates, or Remote Desktop connections through VPN. In most cases, the server itself still works correctly, but Windows now performs much stricter certificate and encryption validation.<\/p>\n
The main reason behind the warnings is stricter validation of RDP certificates and encrypted connections.<\/p>\n
Windows now checks:<\/p>\n
Because of this, even working RDP servers may now trigger security warnings.<\/p>\n
This method works in most cases if the server actually belongs to your company and the issue is only related to the certificate.<\/p>\n
In most situations, this is not caused by malware or hacking attempts. The issue comes from outdated RDP configurations combined with new Windows security requirements.<\/p>\n
Many servers use automatically generated Windows RDP certificates. After the updates, Windows started treating these certificates as less trustworthy.<\/p>\n
This commonly affects:<\/p>\n
If users connect using an IP address while the certificate was issued for a hostname, Windows will display a warning.<\/p>\n
Example:<\/p>\n
After the May 2026 updates, Windows began checking this much more aggressively.<\/p>\n
Some older servers still use TLS 1.0 or TLS 1.1.<\/p>\n
The new updates started to:<\/p>\n
In many cases, this completely resolves the problem.<\/p>\n
This often removes the warning after the 2026 updates.<\/p>\n
This is the best long-term solution for business environments.<\/p>\n
After the May 2026 updates, clearing the RDP certificate cache on the client computer often fixes the issue.<\/p>\n
In many cases, the warning disappears immediately afterward.<\/p>\n
One common mistake is completely disabling certificate validation. This lowers server security and increases risks.<\/p>\n
Another mistake is continuing to use outdated Windows Server installations without security updates.<\/p>\n
Usually not. In most cases, this is simply caused by the new Windows security checks.<\/p>\n
Yes. Proper certificate configuration and correct server naming usually solve the problem.<\/p>\n
Microsoft strengthened RDP security validation in May 2026.<\/p>\n
If this is your own server, usually yes. If the server is unknown, you should verify it first.<\/p>\n
Usually the problem is not related to the RDP client itself but to the server certificate.<\/p>\n
The May 2026 Windows updates significantly increased Remote Desktop security checks. As a result, many users started seeing \u201cUnverified source\u201d and certificate warnings during RDP connections. In most situations, the issue can be fixed by updating the server, using a proper certificate, and connecting through a DNS hostname instead of an IP address.<\/p>\n