There are some inconsistences in libebook on the one hand and desktopcouch on the other hand. libebook returns sometimes NULL on e_contact_get_const, and desktopcouch failes on NULL passed as second argument to desktopcouch_document_contact_set_* (you can it in the logs).
This patch fixes this issue.
I don't know if that's the only problem: (My logs of evolution-data-server-2.28 are at the end)
This patch should fix the 3 CRITICALs but i don't know where the warning 
'Could not PUT document: Conflict' comes from since i dont know much about the evolution/couchdb/desktopcouch source.

I hope this patch helps and fix the bug

Florian


$ /usr/lib/evolution/evolution-data-server-2.28
evolution-data-server-Message: Starting server
e-data-server-Message: adding type `EBookBackendGoogleFactory'
e-data-server-Message: adding type `EBookBackendVCFFactory'
e-data-server-Message: adding type `ECalBackendFileTodosFactory'
e-data-server-Message: adding type `ECalBackendFileEventsFactory'
e-data-server-Message: adding type `ECalBackendFileJournalFactory'
e-data-server-Message: adding type `EBookBackendLDAPFactory'
e-data-server-Message: adding type `ECalBackendCalDAVEventsFactory'
e-data-server-Message: adding type `ECalBackendCalDAVTodosFactory'
e-data-server-Message: adding type `ECalBackendCalDAVMemosFactory'
e-data-server-Message: adding type `EBookBackendWebdavFactory'
e-data-server-Message: adding type `EBookBackendFileFactory'
e-data-server-Message: adding type `ECalBackendContactsEventsFactory'
e-data-server-Message: adding type `EBookBackendCouchDBFactory'
e-data-server-Message: adding type `ECalBackendHttpTodosFactory'
e-data-server-Message: adding type `ECalBackendHttpEventsFactory'
e-data-server-Message: adding type `ECalBackendHttpMemosFactory'
e-data-server-Message: adding type `ECalBackendGroupwiseTodosFactory'
e-data-server-Message: adding type `ECalBackendGroupwiseEventsFactory'
e-data-server-Message: adding type `ECalBackendGroupwiseJournalFactory'
e-data-server-Message: adding type `ECalBackendGoogleTodosFactory'
e-data-server-Message: adding type `ECalBackendGoogleEventsFactory'
e-data-server-Message: adding type `EBookBackendGroupwiseFactory'
e-data-server-Message: adding type `ECalBackendWeatherEventsFactory'
in server_log_handler
evolution-data-server-Message: Server up and running
impl_GNOME_Evolution_Addressbook_BookFactory_getBook
 + file:///home/florian/.evolution/addressbook/local/system
 => 0x9698e60
impl_GNOME_Evolution_Addressbook_Book_open (0x9698e60)
impl_GNOME_Evolution_Addressbook_BookFactory_getBook
 + file:///home/florian/.evolution/addressbook/local/system
 => 0x96c8d20
impl_GNOME_Evolution_Addressbook_Book_open (0x96c8d20)

(process:21236): libedata-book-WARNING **: impl_GNOME_Evolution_Addressbook_Book_getBookView ((contains "x-evolution-any-field" ""))

e_data_book_respond_get_book_view
book_view file uref 

(process:21236): libedata-book-WARNING **: impl_GNOME_Evolution_Addressbook_Book_getBookView ((contains "x-evolution-any-field" ""))

e_data_book_respond_get_book_view
book_view file uref 
impl_GNOME_Evolution_Addressbook_BookFactory_getBook
 + couchdb://127.0.0.1
 => 0x96bfc30
impl_GNOME_Evolution_Addressbook_Book_open (0x96bfc30)
impl_GNOME_Evolution_Addressbook_Book_getContactList
in server_log_handler

** (process:21236): CRITICAL **: desktopcouch_document_contact_set_company: assertion `company != NULL' failed
in server_log_handler

** (process:21236): CRITICAL **: desktopcouch_document_contact_set_department: assertion `department != NULL' failed
in server_log_handler

** (process:21236): CRITICAL **: desktopcouch_document_contact_set_office: assertion `office != NULL' failed
in server_log_handler

** (process:21236): WARNING **: Could not PUT document: Conflict

^C