A Microsoft file hosting and synchronization service.
This could be related to the following issues:
-A file or folder was uploaded and is too large.
-A file or folder was uploaded and is corrupted.
-A file or folder is being used by another application.
-A file or folder is in a folder that OneDrive cannot sync.
-There is a problem with your OneDrive connection.
To fix this problem, you can try the following:
-Make sure that the file or folder is not too large. The maximum size for a file that can be synced to OneDrive is 100GB.
-Try closing any applications that are using the file or folder (Like documents that are opened).
-Try moving the file or folder to a different location in your OneDrive personal folder.
-Check your internet connection (Low internet connection speeds affects syncing files).
After doing or verifying all of these above, restart OneDrive (quit and open it up again).