Rendering Error

I try to render a file in 6000x4000px and no matter what rendering settings I make, the process is stopped at 50% each time, the remaining time is suddenly 0:01 instead of 2:45 and saving the current progress (screenshot) is not possible.There is no error message, because rendering just stops and the software freezes. I have to close it with the task manager and restart again.

Cloud rendering is also not possible, because I have the following message "Error when retrieving credits" and I have never rendered a cloud file before. But I am logged in and the Creative Cloud App is running fine.