To avoid errors with uploading or downloading files with special characters on OneDrive, here are some things to try:

1. Ensure that the filename does not have any unsupported characters, such as &, #, or %.
2. If the file has been renamed on your computer, ensure that the filename does not exceed 150 characters.
3. Ensure that the path of the file is valid, with no more than 400 characters.
4. Verify that the file has the correct file extension.
5. Empty the recycle bin on your OneDrive before attempting to upload or download a file with special characters.