in the evening i gave lightroom the task to move two big folder to the external drive and to render previews for a third folder and to save metadata for a fourth folder. my thinking was, it would be finished in the morning. in the morning LR said: "could move folder because xyz files already exist in destination folder". i understand, that LR did not copy the file duplicates. but it stopped all other tasks too. it should continue executing all other tasks not effected by one problem, when running into an issue i think.