Error message appearing when downloading an excel file from online module

Good day

I've uploaded a package into production and in the progress to test and ensure the content is right before opening to my audience. In my online content, the user has an option to download an excel file to their local system, When I was testing the link, I'm encountering the following error message:-

"The file is corrupt and cannot be opened". After I click on OK, the file is able to open with no additional concerns.

Does anyone know what is occurring?

Regards

AJ