ERR_CONNECTION_REFUSED when attempting to sign in to Tekla desktop software

Overview

We have identified a sign-in issue affecting some users of Tekla desktop software.
The issue is caused by one or more Windows 11 updates — specifically:

• Security Update: KB5066835
• Non-Security Update: KB5065789

Microsoft has since released a critical hotfix to address this issue.

Sign-In Error Example

When launching Tekla Structures, Tekla Structural Designer or Tekla Tedds, and sign-in credentials are required, an attempt is made to open the Trimble Identity service in the default web browser, but this process fails with the web browser reporting an ERR_CONNECTION_REFUSED error.:

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Resolution Steps

To resolve this issue, please follow the steps below:

1. Restart Your Computer

   Restart your computer to ensure the Microsoft hotfix is properly applied.

2. Verify the Update

   In most cases, the hotfix will install automatically. However, if you continue to experience issues, please verify that your system has applied the latest updates.

   You can find the official Microsoft guidance and steps to manually check for and apply updates in the following documentation:

   Windows 11, version 25H2 – Known issues and notifications | Microsoft Learn

   Windows 11, version 24H2 – Known issues and notifications | Microsoft Learn

   Windows Server 2025 – Known issues and notifications | Microsoft Learn

   These pages include the latest information about affected updates, as well as step-by-step instructions for applying updates manually if they have not installed automatically.

3. Sign In Again

   After restarting, launch your Tekla product and attempt to sign in.

Further Assistance

If the issue persists after completing the steps above, please contact your local support team for further assistance.