Hi Benjamin, my log files look exactly like yours (invalid metadata file messages), but at least I can open the resulting images in the SNAP toolbox. But there is also no choice of the reader to use, if I calculate the sen2cor (v2.0.4) for the 10m resolution, only the 10m bands are shown (although all are calculated).
Additionally, as I wrote in this topic, the corrected images are still shown to me as upside down in SNAP, although the image files itself are correct. There still seem to be some problems with the metadata.
BR
Michael