Cannot upload a opened file

I have a upload function to upload word or pdf file. It works fine. But I just found that if the file is opened, and I upload that file at the same time, the file will not be uploaded successfully.

I would like to know if there are any ways to solve it?

Thank you.

Even an opened file gives read access. There is absolutely no reason why the upload should be failing.

Can you post your upload code?