MacOS (CardDav) to MDaemon (25.5 & 26) not working, due to protocol bug

• R

  Roel New

  5/4/26, 6:52 PM

  I’m trying to sync Apple Contacts on macOS with an MDaemon 25.5.0 (and higher, all tested!) CardDAV account.

  Account setup succeeds and macOS accepts the account. In the macOS CardDAV logs I see:

  syncUseSyncReport:1
  syncMaxMultiGetBatch:50
  syncMaxRequestsPerAddressBook:5
  Preparing to sync 1 containers
  _handleAddsOrModifies:(0 items) removes:(0 items)
  SYNCHRONIZATION ... Error (null)

  So macOS performs a real sync, but ends with 0 items.

  I tested the CardDAV collection manually with curl. A normal CardDAV addressbook-query works and returns all vCards correctly:

  REPORT /webdav/addressbook/
  <card:addressbook-query ...>
  → HTTP/1.1 207 Multi-Status
  → many BEGIN:VCARD entries

  However, Apple MacOS appears to use DAV sync-collection. When I test that manually:

  REPORT /webdav/addressbook/
  <D:sync-collection xmlns:D="DAV:">
    <D:sync-token/>
    <D:sync-level>1</D:sync-level>
    <D:prop><D:getetag/></D:prop>
  </D:sync-collection>

  MDaemon returns:

  HTTP/1.1 400 Bad Request
  <altn:webdav-version>25.5.0</altn:webdav-version>
  <altn:exception>ALTN\DAV\Exception\Bad Request</altn:exception>
  <altn:message>Your browser sent a request that this server could not understand.</altn:message>

  So it looks like:
  - CardDAV itself works  (iPhone is working and other client apps too)
  - vCards are present  (when checking with Curl and other client apps)
  - addressbook-query works
  - macOS uses sync-collection
  - MDaemon returns 400 on sync-collection
  - macOS then completes sync with 0 contacts and no visible error

  Is REPORT sync-collection supposed to be supported for CardDAV in MDaemon 25.5.0?

  Is there a setting to disable sync-report/sync-token support, or is this a known Apple Contacts compatibility issue?
  
  Tested with latest MacOS Tahoe 26.5

  0 likes 0 likes Liked Like

  ---

  2
  Posts

  9
  Views

  Reply

  ---

• A

  Arron Admin Staff

  5/5/26, 6:33 AM

  Sync-collection is not supported.  What else does the log show is happening?  A client should fall back to a normal CardDAV addressbook-query, is macOS not doing that?

  Can you upload a full log that shows macOS attempting to sync the address book?

  What URL do you have configured in macOS to sync the address book?  If you create an Advanced account and point it directly at the addressbook.  For example:  https://mail.mydomain.com/webdav/principals/user@mydomain.com

  or 

  https://mail.mydomain.com/webdav/carddav/mydomain.com/user/

  Is macOS able to sync contacts?

  --
  Arron Caruth

  0 likes 0 likes Liked Like

  ---