Sync is failing, getting "400 expected filesize" errors

9.1.x

#1

I recently started getting errors like the one shown below, when syncing a file to my ownCloud instance.

Jul 17 00:22:50 arldn ownCloud[3526]: {webdav} Exception: {"Message":"HTTP\/1.1 400 expected filesize 188245 got 17408","Exception":"
Sabre\DAV\Exception\BadRequest","Code":0,"Trace":"#0 \/usr\/share\/php\/Sabre\/DAV\/Server.php(1070): OCA\DAV\Connector\Sabre\
File->put(Resource id #410)\n#1 \/usr\/share\/php\/Sabre\/DAV\/CorePlugin.php(511): Sabre\DAV\Server->updateFile('Misc\/328 mainte.
..', Resource id #410, NULL)\n#2 [internal function]: Sabre\DAV\CorePlugin->httpPut(Object(Sabre\HTTP\Request), Object(Sabre\HTT
P\Response))\n#3 \/usr\/share\/php\/Sabre\/Event\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#4 \/usr\/share\/p
hp\/Sabre\/DAV\/Server.php(459): Sabre\Event\EventEmitter->emit('method:PUT', Array)\n#5 \/usr\/share\/php\/Sabre\/DAV\/Server.php(
248): Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))\n#6 \/usr\/share\/owncloud\/apps\
/dav\/appinfo\/v1\/webdav.php(61): Sabre\DAV\Server->exec()\n#7 \/usr\/share\/owncloud\/remote.php(164): require_once('\/usr\/share
\/ownc...')\n#8 {main}","File":"\/usr\/share\/owncloud\/apps\/dav\/lib\/Connector\/Sabre\/File.php","Line":149,"User":"bob"}

The server is ownCloud 9.1.5 running on Centos 7.3. I only see this issue when my desktop Windows 10 system attempts to sync to the ownCloud server. My laptop running Fedora 26 syncs just fine, my Android phone syncs just fine, and a Windows 10 VM syncs just fine. I get the problem on the Win 10 desktop whether syncing using the web interface or using the ownCloud client. I looked back in the server's syslog and there were a few similar "HTTP 1.1 400 expected filesize" errors last month, but within the past week, most uploads are now giving this error.

I've looked at https://github.com/owncloud/core/issues/9832, but nothing there was very helpful.