Couldn't load model schema

I installed Power BI Desktop (win 10 / PBI Product Version: 2.56.5023.1021). The first session was okay, but since the second one, I get the error message "Couldn't load model schema" every time, when I want to open an existed .pbix file. I reinstalled the software several times, but the problem is still the same every time.

- I use the latest release of Power BI.

- I'm not sure if it is a relevant info but I'm using SQL Server Express 2017 without SSAS.

- I have VPN on my laptop, but it is not runing

Thank you in advance,