by Joachim S.
Thanks for your investigation. I appreciate your support, as well as the support of Visvanath Ratnaweera. My question was related only to one course. The course is quite simple, it holds only some H5Ps, a quiz and a certificate. Meanwhile I could import those items one by one to 3.10.10. So the problem is resolved for me and this ticket can be closed.
Thanks once more!
Thanks once more!