Bug 488434

Summary: Quite much "kf.kio.core: An error occurred during write" output in syslog
Product: [Applications] dolphin Reporter: nttkde <watisthispoo>
Component: generalAssignee: Dolphin Bug Assignee <dolphin-bugs-null>
Status: REPORTED ---    
Severity: normal CC: kfm-devel
Priority: NOR    
Version: 24.05.0   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description nttkde 2024-06-12 23:04:48 UTC 
Filing this bug initially to Dolphin as it seems to be triggering it (I haven't at least yet noticed other apps causing it but it's possible) but feel free to move to kio if it's definitely not a Dolphin bug.


kioworker[324665]: kf.kio.core: An error occurred during write. The worker terminates now.

At least opening a new tab or refreshing a folder rapidly may cause the line appear in syslog.
There aren't any other side effects that I'd have noticed.


I believe this regression started with Plasma 6 release, I didn't spot it in Plasma 5.

Operating System: KDE neon 6.0
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.2.0
Qt Version: 6.7.0
Kernel Version: 5.15.0-112-generic (64-bit)
Graphics Platform: Wayland

As the error message is quite nondescript, let me know if I could somehow further debug its source.
Comment 1 nttkde 2024-08-23 19:11:35 UTC 
Looks like the error is printed from from SlaveBase::send() in frameworks/kio/src/core/slavebase.cpp.
Printing cmd and arr when the error is printed seem to every time have values cmd: 102 and arr seems to contain string "Cannot create thumbnail for directory".
Comment 2 nttkde 2024-08-23 22:15:29 UTC 
Looking a bit more carefully into the source of the error, SlaveBase::send seems to call 
-> Connection::send() [kio/src/core/connection.cpp] -> Connection::sendnow() -> ConnectionBackend::sendCommand() [kio/src/core/connectionbackend.cpp]
which then sometimes returns false with socket->state() being QLocalSocket::UnconnectedState.

And newer Dolphin/KIO now logs a PeerClosedError right before the 'write' error:
kioworker[329483]: kf.kio.core.connection: Socket not connected QLocalSocket::PeerClosedError
kioworker[329483]: kf.kio.core: An error occurred during write. The worker terminates now.