zed-industries/zed · error

Can't call ScapDefaultTargetCaptureSource::stream multiple t

Error message

Can't call ScapDefaultTargetCaptureSource::stream multiple times.

What it means

Assertion in ScapDefaultTargetCaptureSource::stream: a second stream was requested while one already exists (the one-shot channel was closed after the first call). The scap screen-capture source supports only a single active stream per target.

Source

Thrown at crates/gpui/src/platform/scap_screen_capture.rs:191

            resolution: self.size,
            label: None,
            is_main: None,
            id: self.target.id as u64,
        })
    }

    fn stream(
        &self,
        foreground_executor: &ForegroundExecutor,
        frame_callback: Box<dyn Fn(ScreenCaptureFrame) + Send>,
    ) -> oneshot::Receiver<Result<Box<dyn ScreenCaptureStream>>> {
        let (tx, rx) = oneshot::channel();
        match self.stream_call_tx.try_send((tx, frame_callback)) {
            Ok(()) => {}
            Err(std::sync::mpsc::TrySendError::Full((tx, _)))
            | Err(std::sync::mpsc::TrySendError::Disconnected((tx, _))) => {
                // Note: support could be added for being called again after end of prior stream.
                tx.send(Err(anyhow!(
                    "Can't call ScapDefaultTargetCaptureSource::stream multiple times."
                )))
                .ok();
            }
        }
        to_dyn_screen_capture_stream(rx, foreground_executor)
    }
}

fn new_scap_capturer(target: Option<scap::Target>) -> Result<scap::capturer::Capturer> {
    scap::capturer::Capturer::build(scap::capturer::Options {
        fps: 60,
        show_cursor: true,
        show_highlight: true,
        // Note that the actual frame output type may differ.
        output_type: scap::frame::FrameType::YUVFrame,
        output_resolution: scap::capturer::Resolution::Captured,
        crop_area: None,

View on GitHub (pinned to f4178619ac)

Solutions

1. Create a new ScapDefaultTargetCaptureSource for each capture session instead of reusing one
2. Stop the previous stream and wait for it to fully tear down before calling stream again
3. Guard call sites so only one stream is started per capture source

When it happens

Trigger: Thrown at crates/gpui/src/platform/scap_screen_capture.rs:191 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/34b40c1feca5657d. Report an issue: GitHub.