I went back in time using F-droid’s dev archive, testing all the way to around when 3.9.2 was released (2019-12-07), and the issue persisted, so this is indeed some weird interaction with the latest server version(s) and particularly the conflicts detection thereof.

Version 20191206 (2019-12-07) exhibited the issue a bit differently, though probably just due to how handling of conflicts on the client end has changed between then and now: one file that did go through got renamed with ”(1)” added to it, even though there was no previously existing copy on the server. A previous attempt to upload the same file (using another client version) had failed, so that’s one possible explanation for why the server thought that a previous copy did exist.

Another file got seeminly stuck in the (client upload) queue, and watching the server log revealed that it was incrementing the added number continuously, always coming up with the same ”could not be located” exception from Sabre\DAV as above. It had run up to 80 when I cancelled the upload from the client, and would have perhaps run indefinitely if I didn’t.

{"reqId":"SmCGdnw4BzFQ5P25wMGV","level":0,"time":"2020-11-20T17:40:54+02:00","remoteAddr":"REDACTED","user":"testituutti","app":"webdav","method":"HEAD","url":"/varasto/remote.php/webdav/Testidataa/DSC_0003%20(75).JPG","message":{"Exception":"Sabre\\DAV\\Exception\\NotFound","Message":"File with name Testidataa/DSC_0003 (75).JPG could not be located","Code":0,"Trace":[{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":81,"function":"getNodeForPath","class":"OCA\\DAV\\Connector\\Sabre\\ObjectTree","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpGet","class":"Sabre\\DAV\\CorePlugin","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":474,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":262,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpHead","class":"Sabre\\DAV\\CorePlugin","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":474,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":251,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":319,"function":"start","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/apps/dav/appinfo/v1/webdav.php","line":84,"function":"exec","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/remote.php","line":167,"args":["REDACTED/www/varasto/apps/dav/appinfo/v1/webdav.php"],"function":"require_once"}],"File":"REDACTED/www/varasto/apps/dav/lib/Connector/Sabre/ObjectTree.php","Line":173,"CustomMessage":"--"},"userAgent":"Mozilla/5.0 (Android) Nextcloud-android/20191207","version":"20.0.1.1"}
{"reqId":"M3RTK4KRuOH3N0xGrp2Q","level":0,"time":"2020-11-20T17:41:00+02:00","remoteAddr":"REDACTED","user":"testituutti","app":"webdav","method":"HEAD","url":"/varasto/remote.php/webdav/Testidataa/DSC_0003%20(76).JPG","message":{"Exception":"Sabre\\DAV\\Exception\\NotFound","Message":"File with name Testidataa/DSC_0003 (76).JPG could not be located","Code":0,"Trace":[{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":81,"function":"getNodeForPath","class":"OCA\\DAV\\Connector\\Sabre\\ObjectTree","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpGet","class":"Sabre\\DAV\\CorePlugin","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":474,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":262,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpHead","class":"Sabre\\DAV\\CorePlugin","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":474,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":251,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/3rdparty/sabre/dav/lib/DAV/Server.php","line":319,"function":"start","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/apps/dav/appinfo/v1/webdav.php","line":84,"function":"exec","class":"Sabre\\DAV\\Server","type":"->"},{"file":"REDACTED/www/varasto/remote.php","line":167,"args":["REDACTED/www/varasto/apps/dav/appinfo/v1/webdav.php"],"function":"require_once"}],"File":"REDACTED/www/varasto/apps/dav/lib/Connector/Sabre/ObjectTree.php","Line":173,"CustomMessage":"--"},"userAgent":"Mozilla/5.0 (Android) Nextcloud-android/20191207","version":"20.0.1.1"}