Bug 513673 - Plasmashell crashes attempting screencast on stale window IDs from PipeWire sessions
Summary: Plasmashell crashes attempting screencast on stale window IDs from PipeWire s...
Status: NEEDSINFO BACKTRACE
Alias: None
Product: plasmashell
Classification: Plasma
Component: general (other bugs)
Version First Reported In: 6.5.4
Platform: Arch Linux Linux
: NOR crash
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-12-21 19:51 UTC by 0byte
Modified: 2026-01-06 03:47 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
the right obs instance shows the bug, where the recording freezes as soon as I hover over a taskbar icon widget (3.40 MB, video/mp4)
2025-12-21 19:51 UTC, 0byte
Details

Note You need to log in before you can comment on or make changes to this bug.
Description 0byte 2025-12-21 19:51:10 UTC
Created attachment 187856 [details]
the right obs instance shows the bug, where the recording freezes as soon as I hover over a taskbar icon widget

SUMMARY
Plasmashell crashes when attempting to create screencast thumbnails for stale window IDs from closed PipeWire sessions. With "Show tooltips" enabled in task manager, hovering over taskbar icons triggers crash. With tooltips disabled, OBS recording freezes instead.

STEPS TO REPRODUCE
1. Start OBS with PipeWire screen capture source (Screen1)
2. Close OBS (leaves stale PipeWire screencast session/window ID)
3. Start new OBS instance or reuse existing OBS scene with same Screen1 source
4. Start recording in OBS
5. Hover mouse over taskbar icons in task manager widget

OBSERVED RESULT
**With "Show tooltips" enabled:**
- Plasmashell logs: `error creating screencast "Could not find window id {UUID}"`
- Plasmashell crashes (segfault, signal 11)
- DrKonqi crash handler appears
- Plasmashell auto-restarts but stale window ID persists
- Crash repeats on subsequent hovers

**With "Show tooltips" disabled:**
- No plasmashell crash
- PipeWire stream in OBS changes state from "streaming" to "paused" after ~10-15 seconds
- OBS recording freezes (no new frames captured)
- journalctl shows: `[pipewire] Stream 0x... state: "paused" (error: none)`
- Requires OBS restart to resume recording

**Key observation:** 
The stale window UUID persists across plasmashell restarts. In my testing, UUID `{d0df4bc8-e137-4a44-b342-708029333b2d}` appeared repeatedly in logs even after multiple plasmashell crashes/restarts.

EXPECTED RESULT
- Plasmashell should handle missing/stale window IDs gracefully without crashing
- Closed PipeWire screencast sessions should be cleaned up properly
- Task manager tooltips should skip preview generation for non-existent windows
- Active OBS recordings should not freeze due to unrelated screencast errors

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux, Kernel 6.17.9-arch1-1
KDE Plasma Version: 6.5.4
KDE Frameworks Version: (run `kinfo` if available)
Qt Version: 6.10.1
GPU: NVIDIA GeForce RTX 3090, Driver 580.105.08
Session: Wayland
OBS Version: 32.0.2
PipeWire Version: 1.4.9

ADDITIONAL INFORMATION
- Video recording attached showing two OBS instances side-by-side:
  - **Right instance (old):** Contains "Screen1" source copied from previous scenes - bug reproduces consistently
  - **Left instance (new/fresh):** Newly created Screen1 source - bug does NOT happen with tooltips disabled, but DOES crash with tooltips enabled
- This suggests the stale window reference is embedded in OBS scene data or PipeWire session state
- Clearing PipeWire state (`rm -rf ~/.local/state/wireplumber/*`) and restarting services does NOT fix the issue
- The issue does not occur on X11 sessions (Wayland-specific)
- Related to bugs #480313 and #478518 (similar "Could not find window id" screencast errors)

**Logs excerpt:**

Dec 21 20:16:20 devwhite obs[117638]: info: [pipewire] Stream 0x... state: "paused" (error: none) Dec 21 20:16:20 devwhite plasmashell[111982]: error creating screencast "Could not find window id {d0df4bc8-e137-4a44-b342-708029333b2d}" Dec 21 20:17:01 devwhite plasmashell[111982]: KCrash: Application 'plasmashell' crashing... crashRecursionCounter = 2 Dec 21 20:17:01 devwhite systemd[4716]: plasma-plasmashell.service: Main process exited, code=dumped, status=11/SEGV

^ completely ai generated text but I had these problems for months now, a solution is to only use window captures or not hover the taskbar icons at all which is not really a solution
Comment 1 TraceyC 2025-12-22 22:08:01 UTC
Thanks for the crash report. As the message at the top of the summary says, if something crashed, we need a backtrace of it so we can figure out what's going on. From what you wrote, I see plasmashell was what crashed. Can you please attach a backtrace of the crash using the coredumpctl command-line program, as detailed in https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports#Retrieving_a_backtrace_using_coredumpctl ?

Thanks.
Comment 2 Bug Janitor Service 2026-01-06 03:47:00 UTC
๐Ÿ›๐Ÿงน โš ๏ธ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!