Consider the following scenario:
You have a Microsoft SharePoint Server 2013 subsite.
The subsite has unique permissions that aren't inherited from the parent site collection.
The Limited-access user permission lockdown mode site collection feature is enabled for the parent site collection where the subsite exists.
You share a list on the subsite with a user, and you provide at least edit permissions.
When the user tries to add a file to the list by using the drag files here functionality, he or she receives the following error message:
Error with request to the server: Access denied. You do not have permission to perform this action or access this resource.
To work around this issue, click new document, click UPLOAD EXISTING FILE, and then follow the steps in the Add a document dialog box to add files to the list.
For more information, go to the following Microsoft websites: