RDCM lost local resources (disks) in version 2026.8.19

Hello,

What you are seeing is a change in behavior introduced by recent Remote Desktop Connection Manager (RDCMan) updates. The client now enforces stricter certificate validation. When the RDP server presents a certificate that is not trusted by the local machine, RDCMan blocks redirection of local resources such as drives, printers, and clipboard. This is by design, as Microsoft tightened security to prevent man‑in‑the‑middle attacks and resource hijacking.

To restore functionality, you need to ensure the RDP server’s certificate is trusted on the client side. Export the server’s TLS certificate and import it into the client’s Trusted Root Certification Authorities store (certmgr.msc → Certificates – Current User → Trusted Root Certification Authorities → Certificates → Import). Alternatively, if the server is using a self‑signed certificate, regenerate it with proper CN/SAN values matching the server’s hostname, then deploy it to clients. Certificates issued by a recognized CA will work without manual trust installation.

There is no supported way to bypass this check in RDCMan anymore. Editing registry keys under HKCU\Software\Microsoft\Terminal Server Client or disabling certificate validation is not recommended, as Microsoft has explicitly hardened this path. The only reliable solution is to align certificates with trusted roots. If you are in a domain environment, you can push the certificate via Group Policy under Computer Configuration → Windows Settings → Security Settings → Public Key Policies → Trusted Root Certification Authorities.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

HP.