Fix RDP Security Warnings

Install Connection Client to trust signed remote desktop connections

Why am I seeing a warning?
Starting with the April 2026 Windows security update, Remote Desktop Connection shows a new security dialog every time you open a .connect file. Unsigned or untrusted connection files display "Unknown publisher" or ask you to verify the publisher. Learn more from Microsoft.

What you may see

After the April 2026 update, Windows shows these dialogs when you open a .connect file. Installing Connection Client fixes the Unknown publisher warning shown below.

1. First-time connection file prompt

The first time you open a .connect file on your account, Windows shows an educational dialog. Check the box "I understand and allow RDP files to open on this device for my account", then click OK. This appears once per user account.

Remote Desktop Connection first launch dialog asking to allow RDP files

2. Unknown publisher warning

Every time you open a .connect file, a security dialog appears. If the signing certificate is not trusted on your PC, the Publisher shows as "Unknown publisher" with a "Caution: Unknown remote connection" banner. This is what Connection Client fixes — after installation, your signed connection files are trusted automatically.

Remote Desktop Connection security warning showing Unknown publisher

What this installer does

The Connection Client setup installs the Remote Access Client certificate (Remote Access Client.cer) into your computer's Trusted Root Certification Authorities store. This allows Windows to verify the publisher when you open .connect files signed by your organization. The setup also enables Remember my choices for remote connections from this publisher, so you connect normally without seeing the security dialog each time.

Start here

Download the setup file

Click the blue button below to download the installer.

You must download and run this file on the computer where you connect via Remote Desktop.

⬇ Click here to download Setup-ConnectionClient.exe

After downloading, open the file from your Downloads folder, then follow the installation steps below.

Installation steps (after downloading)

If Connection Client is already on your computer, the wizard starts at Ready to Install and includes an RDP certificate configuration step.

  1. Click Install

    On the Ready to Install screen, click Install to begin upgrading Connection Client.

    Ready to Install screen

  2. Configure RDP signature trust

    On the RDP Signature Trust Configuration screen, click Configure now (requires admin). This installs the signing certificate and registers it as a trusted RDP signer so you no longer see security warnings.

    RDP Signature Trust Configuration screen

  3. Confirm configuration succeeded

    When the Configuration applied successfully message appears, click OK, then click Next on the configuration screen.

    Configuration applied successfully dialog

  4. Virtual Printer (optional)

    If you see a message that the Virtual Printer Client is not installed, you can safely click Next. The Virtual Printer is optional and not required to fix the connection warning.

    Virtual Printer optional screen

  5. Click Finish

    When you see Completing the Connection Client Setup Wizard, click Finish to close the installer.

    Setup complete screen

If Connection Client has never been installed on this computer, follow these steps.

  1. Select Install for all users

    When prompted, choose Install for all users (not "Install for me only"). This requires administrator privileges and ensures the certificate is installed for the entire system.

    Select Install for all users

  2. Approve the security prompt

    Windows User Account Control will ask whether to allow the app to make changes. Click Yes to continue.

    Click Yes on User Account Control

  3. Virtual Printer (optional)

    If you see a message about the Virtual Printer Client not being installed, you can safely click Next to continue. The Virtual Printer is optional and not required to fix the connection warning.

    Click Next on Virtual Printer screen

  4. Click Install

    On the "Ready to Install" screen, click Install to begin. Wait for the installation to finish.

    Click Install on Ready to Install screen

  5. Click Finish

    When you see "Completing the Connection Client Setup Wizard", click Finish to close the installer.

    Click Finish on Completing the Connection Client Setup Wizard
Done! After installation, open your .connect file again. The remote session should start normally, just like before the Windows update — no security dialog. The setup trusts the publisher certificate and remembers your choice for future connections.