Archicad 27/Win not working

Archicad 27 does not work.
The installation of Speckle Connection went well.
However, when running it within Archicad, this error appears:
“Error! Unable to start Speckle interface (Speckle UI).”

Has anyone managed to solve this?

Which platform have you installed to, e.g. macOS, Windows (including version)?

My operating system is Windows 11

We should probably check the installation paths first. If you open the Add-On manager (from the Options menu) and select “Speckle Connector AddOn”, does the path to the add-on look something like this:

If so, can you open File Explorer to that path and navigate to the AppData\Roaming\Speckle\Archicad\Common path (as shown below) and check that it contains a directory called “ConnectorArchicad”?