I tried running a backup, my laptop went to sleep and now it seems stuck on a file (for several hours). I tried to click cancel after current file and also cancel now, but neither does anything and it just shows “Cancelling after current file” for hours. What to do?
Welcome to the forum @Kiwi
Although it won’t fix things, a good first step is to see what the logs say has been happening recently.
Viewing the Duplicati Server Logs at About → Show log → Live → Profiling would give highest detail.
About → System info → Server state properties can be even harder to interpret, but if there’s a lastPgEvent still hanging around, it might give some information.
Just to the right of that is a pause/resume button. Is it ready for you to pause now? That would be 
The easiest question is – what does the status bar at the top of the main GUI screen say is going on?
EDIT: to try that again, do you know what it was saying before you requested that the cancel be done?
What are you backing up from and to (meaning what is your backup screen 2 Storage Type set to)?