A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi R,
For the PDF that cannot load, we suggest you check the file size see if it uploaded successfully. If the file size is right, you could open a private window in your browser and open the PDF see if the error still persists. If the fPDF did not upload to the library, we suggest you upload the file individually to see if the issue persists.
The best practice to upload multiple folders and files is using the OneDrive Sync Client and sync the SharePoint library then operate in File Explorer in Windows.
Sync files with the OneDrive sync client in Windows.
Sync SharePoint files with the new OneDrive sync client.
Then you could open File Explorer and copy or move the files.
About the error messages you mentioned when you shtat the process, there are some Restrictions and limitations syncing files and folders to OneDrive and SharePoint. You could check this article first: Restrictions and limitations when you sync files and folders. For further support, could you share a screenshot of the error message with us?
Regards,
Alex