Cannot open nor create termbase on SDL Multiterm 2019 and Windows 10 Pro

When trying to open a termbase I get following messages:  This termbase cannot be opened because it has been created with an unsupported version ot Multiterm. It is SDL Studio 2019 on Windows 10 Pro. I uninstalled the OneDrive App on my device. The problem persists. Please help me! I’m devastated...