Sending multimedia content and documents within chat conversations in Microsoft Teams
Yes. In Teams, that behavior is expected for guests in chat.
A guest can:
- participate in private chat
- download private chat files
- share a channel file
- access SharePoint files
A guest cannot:
- share a chat file
- use OneDrive for Business storage
That matches the errors shown:
- “Your OneDrive isn’t available”
- “Sorry, you need OneDrive to share files”
Teams chat file sharing relies on OneDrive/SharePoint. Since guests don’t have OneDrive for Business storage in the host organization, they can’t attach files directly in chat the same way internal users can.
What works instead:
- Use a channel instead of chat if the team allows it. Guests can share a channel file.
- Ask a member of the organization to share the file location or upload it on behalf of the conversation.
- Use a secure SharePoint link if the organization shares files externally that way.
If this is an external/federated chat rather than guest access, file upload in chat depends on whether the organization has enabled file sharing in external chats. When file sharing is off, users can only paste existing links and can’t upload files directly.