Item does not exist
This message shows up in 2 different situations. Pick the one that matches yours:
- A drop box for sensitive files — a document library can't do it, a list with ReadSecurity 2 and attachments can (measured, including the direct attachment URL)Giving someone write access to a protected library folder also lets them read every file in it; a list with ReadSecurity = 2, Contribute for the senders and Edit for the reviewers lets people send files they alone can see — the direct attachment URL of someone else's item is denied in SharePoint Online (measured)Cause and fix →
- Previewing library files in your own app: every format behaves differentlyPDF embeds directly, Office needs WOPI by {UniqueId}, HTML is served as an attachment and never renders from src; SVG and HTML must never be framed from your own origin (uploader script runs in the viewer session) and OneDrive refuses framing with no way to detect it; ?web=1 on a PDF ends on AccessDenied for users with access only to the file or its folderCause and fix →