Steps to reproduce
1. Connect read-only, locally connected external storage on owncloud server version 8.1.x containing files whose file names contain some characters unknown in the ISO8859-1 encoding.
2. Allow desktop client to sync and produce an error relating to the strange characters (sorry - not sure what they were, they appeared as a '?'). File names containing the strange characters did not sync to the client.
3. Regenerate(*) those files whose file names contained strange characters using a UTF-8 character encoding and allow desktop client to sync again.
4. (optional) Upgrade owncloud server from 8.1.x t 9.0.8 (current stable) and run occ files:scan --all (which completed without error)
(*) The regeneration process was: a) delete file b) convert a flac file into mp3 format using lame and use iconv --to-code=UTF-8 to create the file name for the mp3.
After regenerating the files on the server-side, they will be re-downloaded on the client-side and there will be no errors in the client settings window.
The server-side files are indeed updated on the client-side with the correct file names, but there is a list of errors like:
mp3/Paul Lewis/Schubert - Piano Sonata D.845 - Wandererfantasie D.760 - etc - CD2 (2012)/03 - - Scherzo. Allegro vivace - Trio. Un poco piu: File was deleted from server
(in that example it was an accented u in "piu" which caused the need for re-naming the file)
The errors won't disappear on the client and the owncloud icon in the taskbar has a red cross.
I am currently syncing the files onto another machine to see if the errors will appear there. This will take about two days.
Client version: 2.3.1
Client operating system: Ubuntu 16.04
Operating system: Debian 8 (Jessie)
Web server: Apache2 2.4.10 (standard Debian package)
Database: Mysql-5.5 (standard Debian package)
PHP version: 5.6.30 (standard Debian package)
ownCloud version (see ownCloud admin page): 9.0.8
Updated from an older ownCloud or fresh install: Updated
Special configurations (external storage, external authentication, reverse proxy, server-side-encryption): Uses external storage to share specific folders read-only, otherwise fairly standard installation.
ownCloud log (data/owncloud.log)
Please paste possible errors in the following code block, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808 for more info
No server logs are generated for these files.