Since I have updated from 0.8.4.1 to 0.9.0.4 via F-Droid a few days ago, all syncing stopped without giving an error, notification, etc. I uninstalled and reinstalled DAVdroid and now I get an error when I try to add a new account which says something along the lines of “No calendars or address books found” (I don’t remember the exact wording). The error log consists of many PROPFIND runs, all looking like:
[debug] PROPFIND on user-given URL failed - EXCEPTION:
java.io.IOException: stream was reset: PROTOCOL_ERROR
and so on. I use OwnCloud with a certificate from CAcert and have installed their root certificates to /system/etc/security/cacerts/. Before having installed the certs DAVdroid asked whether I accept the unknown server certificate, I clicked yes and received the same error.
You can try to reproduce the issue under the URL: https://pim.devkid.net/. Using the old version 0.8.4.1 still works. Opening the URL directly in a browser (ASOP browser) also works, however opening in Firefox for Android gives an error sec_error_cert_signature_algorithm_disabled, which might be related to this problem.