I am using Nextcloud inside a Docker container running in a Raspberry PI 4. After all the installation process and configuration, I installed the windows 10 client and moved the folders with all the files that I wanted to synchronize with my RPi Server.
Unfortunately I noticed that many of the files were not synchronizing and showing an “x” in the windows 10 file icon like: 
How can I solve this problem? In the Logging Section in the Web interface I dont see any error when syncing one particular file (with the X).
Thanks and greetings!
What does the Windows 10 client log say? There should be notifications about the sync errors.
Also, how big are the files we are talking about? NCP has a file size limit if I’m not mistaken.
So I found how to see the log in windows and this is the output when changing the name (tarea_2.txt to tarea_3.txt) from one of the files with the X mark :
2020-12-21 19:12:54:988 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:NOP:C:\Users\bruno\Nextcloud\tarea_3.txt” to QLocalSocket(0x2543138e4f0)
2020-12-21 19:12:54:988 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:NOP:C:\Users\bruno\Nextcloud\tarea_3.txt” to QLocalSocket(0x2542f1d9ad0)
2020-12-21 19:12:54:988 [ debug nextcloud.sync.database.sql ] [ OCC::SqlQuery::bindValue ]: SQL bind 1 QVariant(qlonglong, 810913366661168183)
2020-12-21 19:12:54:989 [ debug nextcloud.sync.database.sql ] [ OCC::SqlQuery::exec ]: SQL exec “SELECT path, inode, modtime, type, md5, fileid, remotePerm, filesize, ignoredChildrenRemote, contentchecksumtype.name || ‘:’ || contentChecksum, e2eMangledName, isE2eEncrypted FROM metadata LEFT JOIN checksumtype as contentchecksumtype ON metadata.contentChecksumTypeId == contentchecksumtype.id WHERE phash=?1”
2020-12-21 19:12:54:989 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:NOP:C:\Users\bruno\Nextcloud\tarea_2.txt” to QLocalSocket(0x2543138e4f0)
2020-12-21 19:12:54:989 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:NOP:C:\Users\bruno\Nextcloud\tarea_2.txt” to QLocalSocket(0x2542f1d9ad0)
2020-12-21 19:12:54:990 [ debug nextcloud.sync.database ] [ OCC::SyncJournalDb::commitInternal ]: Transaction commit “post treewalk” and starting new transaction
2020-12-21 19:12:54:990 [ debug nextcloud.sync.database.sql ] [ OCC::SqlQuery::exec ]: SQL exec “SELECT tmpfile, etag, errorcount, path FROM downloadinfo”
2020-12-21 19:12:54:991 [ debug nextcloud.sync.database.sql ] [ OCC::SqlQuery::exec ]: SQL exec “SELECT path,transferid FROM uploadinfo”
2020-12-21 19:12:54:991 [ debug nextcloud.sync.database.sql ] [ OCC::SqlQuery::exec ]: SQL exec “SELECT path FROM blacklist”
2020-12-21 19:12:54:992 [ debug nextcloud.sync.database ] [ OCC::SyncJournalDb::commitInternal ]: Transaction commit “post stale entry removal” and starting new transaction
2020-12-21 19:12:54:992 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:SYNC:C:\Users\bruno\Nextcloud” to QLocalSocket(0x2543138e4f0)
2020-12-21 19:12:54:992 [ info nextcloud.gui.socketapi ]: Sending SocketAPI message --> “STATUS:SYNC:C:\Users\bruno\Nextcloud” to QLocalSocket(0x2542f1d9ad0)
2020-12-21 19:12:54:992 [ info nextcloud.sync.engine ]: #### Post-Reconcile end #################################################### 22157 ms
2020-12-21 19:12:55:107 [ info nextcloud.gui.folder ]: #### Propagation start ####################################################
2020-12-21 19:12:55:107 [ debug nextcloud.gui.socketapi ] [ OCC::SocketApi::slotUpdateFolderView ]: Not sending UPDATE_VIEW for “1” because status() is 3
I dont see a particular error or maybe I am blind. The file is only 1KB big, so I dont think that is the problem.