[Push subscription] Nextcloud parse errors

[m-i-k-e-y]

Since early or mid February, I started to see the following errors in my Nextcloud instance (they always happen in pair), which seem to be caused by DAVx while syncing contacts (I guess ?) :

{
  "reqId": "aUJFsMdvDD6RYD07m58Z",
  "level": 3,
  "time": "2026-03-12T14:07:49+00:00",
  "remoteAddr": "redacted",
  "user": redacted",
  "app": "no app in context",
  "method": "POST",
  "url": "/remote.php/dav/addressbooks/users/redacted/contacts/",
  "scriptName": "/remote.php",
  "message": "Uncaught exception",
  "userAgent": "DAVx5/4.5.9-gplay (dav4jvm; okhttp/5.3.2) Android/16",
  "version": "32.0.6.1",
  "exception": {
    "Exception": "Sabre\\Xml\\ParseException",
    "Message": "The input element to parse is empty. Do not attempt to parse",
    "Code": 0,
    "Trace": [
      {
        "file": "/var/www/nextcloud/apps/dav_push/lib/Dav/SubscriptionManagementPlugin.php",
        "line": 198,
        "function": "parse",
        "class": "Sabre\\Xml\\Service",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/3rdparty/sabre/event/lib/WildcardEmitterTrait.php",
        "line": 89,
        "function": "httpPost",
        "class": "OCA\\DavPush\\Dav\\SubscriptionManagementPlugin",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 472,
        "function": "emit",
        "class": "Sabre\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/lib/Connector/Sabre/Server.php",
        "line": 212,
        "function": "invokeMethod",
        "class": "Sabre\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/lib/Server.php",
        "line": 426,
        "function": "start",
        "class": "OCA\\DAV\\Connector\\Sabre\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/appinfo/v2/remote.php",
        "line": 22,
        "function": "exec",
        "class": "OCA\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/remote.php",
        "line": 151,
        "args": [
          "/var/www/nextcloud/apps/dav/appinfo/v2/remote.php"
        ],
        "function": "require_once"
      }
    ],
    "File": "/var/www/nextcloud/3rdparty/sabre/xml/lib/Service.php",
    "Line": 129,
    "message": "Uncaught exception",
    "exception": [],
    "CustomMessage": "Uncaught exception"
  },
  "id": "69b2e8ef734db"
}

{
  "reqId": "aUJFsMdvDD6RYD07m58Z",
  "level": 3,
  "time": "2026-03-12T14:07:49+00:00",
  "remoteAddr": "redacted",
  "user": "redacted",
  "app": "webdav",
  "method": "POST",
  "url": "/remote.php/dav/addressbooks/users/redacted/contacts/",
  "scriptName": "/remote.php",
  "message": "The input element to parse is empty. Do not attempt to parse",
  "userAgent": "DAVx5/4.5.9-gplay (dav4jvm; okhttp/5.3.2) Android/16",
  "version": "32.0.6.1",
  "exception": {
    "Exception": "Sabre\\Xml\\ParseException",
    "Message": "The input element to parse is empty. Do not attempt to parse",
    "Code": 0,
    "Trace": [
      {
        "file": "/var/www/nextcloud/apps/dav_push/lib/Dav/SubscriptionManagementPlugin.php",
        "line": 198,
        "function": "parse",
        "class": "Sabre\\Xml\\Service",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/3rdparty/sabre/event/lib/WildcardEmitterTrait.php",
        "line": 89,
        "function": "httpPost",
        "class": "OCA\\DavPush\\Dav\\SubscriptionManagementPlugin",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 472,
        "function": "emit",
        "class": "Sabre\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/lib/Connector/Sabre/Server.php",
        "line": 212,
        "function": "invokeMethod",
        "class": "Sabre\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/lib/Server.php",
        "line": 426,
        "function": "start",
        "class": "OCA\\DAV\\Connector\\Sabre\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/dav/appinfo/v2/remote.php",
        "line": 22,
        "function": "exec",
        "class": "OCA\\DAV\\Server",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/remote.php",
        "line": 151,
        "args": [
          "/var/www/nextcloud/apps/dav/appinfo/v2/remote.php"
        ],
        "function": "require_once"
      }
    ],
    "File": "/var/www/nextcloud/3rdparty/sabre/xml/lib/Service.php",
    "Line": 129,
    "message": "The input element to parse is empty. Do not attempt to parse",
    "exception": [],
    "CustomMessage": "The input element to parse is empty. Do not attempt to parse"
  },
  "id": "69b2e8ef734ee"
}

There are always 6 pairs of these exceptions at once, every couple of hours.

I don't know if this is a Nextcloud or DAVx issue, as I received updates for both around that time and after that too.

I'm currently on Nextcloud 32.0.6.1 and DAVx 4.5.9-gplay (on a Samsung Galaxy S22+ and a Galaxy Tab S8+).

[rfc2822]

Is this the same as bitfireAT/nc_ext_dav_push#65?

[m-i-k-e-y]

It seems to be the same error as listed in this comment in that issue.
Same version of DAVx, different Nextcloud version ( 32.0.6.1 in my case and 33.0.0.16 in that other issue).
I have DAV Push installed on my Nextcloud Instance, version 1.0.1.

[rfc2822]

Tracked in #2073

The problem is that I can't reproduce the problem and so can't take a look. Please have a look there, especially #2073 (comment) and provide verbose logs if possible

[m-i-k-e-y]

Ok, then I'll close this one. Thanks!