Suspect is that the seeming change of remote volume size to 500MB (up from default 50MB) means the download can’t complete in the default 100 seconds that Duplicati allows for downloads from OneDrive. Actually it’s a Microsoft default, but Duplicati doesn’t change it. You can probably see Duplicati server log About --> Show log --> Retry towards the end of the backup when the verifying backend files step occurs. This samples a dlist, dindex, and dblock for integrity, and you had several backups fail on the large dblock. Looking at the live log should show retries every 110 seconds or so for about 4 tries, then it will give up…
If this is what’s going on, add an –http-operation-timeout at something long enough to get remote volume.
Set remote volume size and http-operation-timeout automatically based on bandwidth #3819 is a request for Duplicati to help the user set things up suitably. I have a feeling most destinations aren’t as sensitive to slow transfers as OneDrive, in fact I suspect some don’t time out. That might harm ability to notice hangs.
Setting timeouts not-too-short but not-too-long is hard. Anyway, I hope your resolution is just a new option.