List folks running Linux: If you're getting something like this: Request Error Access to "New Event" in "calendar" in account "Home Calendars" is not permitted. The server responded: "HTTP/1.1 403 Forbidden" to operation CalDAVScheduleEventQueueableOperation. or [CalDAV Outbox POST] Could not find principal for originator: mailto:whoever@domain.com and your accounts.xml looks something like this: <user> <uid>admin</uid> <guid>admin</guid> <password>admin</password> <name>admin</name> <cuaddr>mailto:admin</cuaddr> </user> Looks like you've got the same problem I ran into... improper GUID's. You need full, system-generated GUID's like: <user> <uid>admin</uid> <guid>16f524a3-356e-54ab-9267-e51ce008e511</guid> <password>admin</password> <cuaddr>mailto:root@thinkcreatesolve.com</cuaddr> <name>Admin</name> </user> If you go to the CalDavd in a web browser (probably http://127.0.0.1:8008 on your Linux server itself), click on "Principals", (you might need your admin password), click on "users", and then click on each user's name, You'll see the following: Principal Details Directory Information --------------------- Directory GUID: 4325319e-0d84-5b06-b703-e45634a2818a Realm: The Family Principal Information --------------------- GUID: 16f524a3-356e-54ab-9267-e51ce008e511 Record type: users Short name: admin Full name: Admin Principal UID: 16f524a3-356e-54ab-9267-e51ce008e511 Principal URL: /principals/__uids__/16f524a3-356e-54ab-9267- e51ce008e511/ It's the "Principal Information: GUID:" line that you'll need in your accounts.xml, for each user. Everything should work fine if you do that! Just a helpful reminder, as someone was asking off-list. Best, David Szego.