@Wine_Merchant Thank you for your response. To be honest, for I’m a new member of this community, I’m not sure, if this issue is related to an outdated doc site. I only recognized that there are a lot of linked contend refering a 404 error page.
If it is related to this old doc site I can understand it. I was asked to migrate content - especialy linked sites of our old share point within a crm system. After several unsuccesful attempts we moved the content manually. So we may close this thread.