## 1 Introduction  
In a survey by Times Higher Education of 200 rectors from the top 1000 universities, \"19 percent think that digital technology will have eradicated physical lectures by 2030, compared with 65 percent who disagree\" [1]. The same study from 2018 also shows that European rectors at top universities agree to a wider extent than their US-American colleagues that digital technology will have eradicated physical lectures (and to a lesser extent than Asian colleagues). These results are from a time before the COVID-19 crisis in spring 2020, when, for the first time, presence teaching was restricted in many universities worldwide.  
Before COVID-19, apart from a few distance learning universities, most European universities were presence, non-distance universities, teaching more or less physical lectures. Nevertheless, for 30 years different formats and forms of technology-supported learning have been used and implemented in European universities [2]: Learning management systems are often standard; lecture recordings as a supplement to lectures are an option, especially for mass courses; some teachers are shifting the transfer of knowledge to videos and use the course for open questions and exercises. Nonetheless, pure online courses are still rarely found. How to communicate, achieve and improve the advantages of e-learning-supported teaching and online teaching is the task and interest of many e-learning centres,university didactic institutions and also research units--and in research publications [3]. There are several considerations and models of how to achieve a high level of use and adaptation of online teaching at presence universities and how to assess universities' e-learning readiness. There are also studies that deal with the resistance against and disadvantages of e-learning in higher education [4].  
The COVID-19 epidemic had the side effect that online teaching received an involuntary boost and was implemented on a broad scale at Graz University of Technology (TU Graz) within a few days. Within this article we describe how this provisional and temporary, but almost complete, conversion of the teaching system to online (remote) teaching, specifically e-learning, has succeeded. We will describe challenges and bottlenecks. From a scientific point of view, we would like to link this to the question of the e-learning readiness model; whether it should be adapted or if this experience confirms them. We also write this article because only after a few days we realized that the way TU Graz reacted was not the only way to deal with the situation; in the neighbouring country of Germany, a large group of professors teaching at universities clarified that they could not teach online but demanded a \"non-semester\" [5].  
Thus, in this article and our case report we focus strongly on (pure) online teaching and e-learning as technology-supported distance learning and not on technology-assisted or enriched face-to-face arrangements [6], and will describe the situation prior to the crisis, the development within in the crisis, and the effects concerning online teaching. Universities around the world are facing similar problems and we thus want to share our experiences and lessons learned. Therefore, we describe the status quo before the COVID-19 crisis and the developments within the first three weeks, and reflect on enablers, barriers and bottlenecks in this contribution.