[SDK 0.24.12112 / VVD] gwsi-tool-screenshooter writes a 0-byte PNG or hangs

Vega Open Beta Bug Reports
1

1. Summary

On the Vega Virtual Device from SDK 0.24.12112, gwsi-tool-screenshooter never produced an image. Amazon staff recommend it for screenshots in topic 27750, and as the VVD workaround in topic 20196. In two sessions it either returned after about 3 s with a 0-byte PNG, or hung until killed, again leaving a 0-byte PNG. Only the launcher was running.

App Name: none; the bug is in a device tool (we build Dice Chess TV)
App Link on Amazon Appstore: not published yet

Bug Severity
Select one that applies

  • Impacts operation of app
  • Blocks current development
  • Improvement suggestion
  • Issue with documentation (If selected, please share the doc link and describe the issue)
  • Other: the screenshot tool recommended here does not work on the Virtual Device

2. Steps to Reproduce

  1. vega virtual-device start --no-gui, and wait for the launcher. Launch no app.
  2. vega exec vda shell gwsi-tool-screenshooter /tmp/shot.png
  3. vega exec vda shell ls -la /tmp/shot.png
  4. Repeat step 2 with another file name.

3. Observed Behavior

Session 1, first run: step 2 returned after 2.7 s with no output, and /tmp/shot.png was 0 bytes.
Session 1, later runs: step 2 did not return. One process was still running after more than
2 minutes, until we killed it. Each run left a 0-byte file, in /tmp and in /data alike.
Session 2, first run after a fresh boot: step 2 was still running after 15 s, with a 0-byte file.

gwsi-tool-screenshooter -h prints usage: gwsi-tool-screenshooter [-h] [FILENAME], so the tool is present.

4. Expected Behavior

A PNG of the screen, as in the staff answer in topic 27750.

4.a Possible Root Cause & Temporary Workaround

Root cause: unknown. The device log has one line from the tool, as it starts, and nothing after it.

Workaround, on the VVD only: the Android emulator underneath the VVD returns the screen through its
own gRPC API (EmulatorController.getScreenshot) once its console has been sent `grpc <port>`.
On the same VVD, at the same time, that returned a 1920x1080 PNG. We call it through
vega-vvd-driver, an unofficial open-source tool: https://github.com/fortemate/vega-vvd-driver
(`vvd enable-grpc`, then `vvd screenshot shot.png`).

5. Logs or crash report

The tool’s only line in the device log (vega exec vda shell loggingctl log -f --since now, session 2), with the device name removed:

Sep 28 20:40:57.115057 <device> daemon.info gwsi-tool-screenshooter[2620]: 20 I Inputd-client:requestPriority:431: Client Requesting Priority 12: WRITE_TO_UDEV

We can send the full log of that run (about 3,000 lines) by PM.

6. Environment

  • SDK Version: 0.24.12112 (Vega CLI 1.3.4)
  • React Native Version: not applicable; no app was running
  • App State: no app; the launcher in the foreground
  • Host: macOS on Apple silicon; the VVD started with --no-gui
  • OS Information:
NAME="OS"
OE_VERSION="4.0.0"
OS_MAJOR_VERSION="1"
OS_MINOR_VERSION="2"
RELEASE_ID="21"
OS_VERSION="1.2"
BRANCH_CODE="TV Ship"
BUILD_DESC="OS 1.2 (TV Ship/102282480)"
BUILD_FINGERPRINT="1.0.228248.0(9a1d8dfa7da5d600)/102282480N:user/dev-keys"
BUILD_VARIANT="user"
BUILD_TAGS="dev-keys"
BUILD_DATE="Fri Sep 18 21:35:23 UTC 2026"
BUILD_TIMESTAMP="1789767323"
VERSION_NUMBER="2111248248030"

7. Example Code Snippet / Screenshots / Screengrabs

Not applicable: no app code is involved.

4

Hi @Fortemate,

Thanks for the detailed report.

The behavior you’re seeing is expected: gwsi-tool-screenshooter is not supported on the Vega Virtual Device. This is documented in the VDA Reference ( VDA Reference - Amazon Vega Docs ): “Vega Virtual Device doesn’t support gwsi-tool-screenshooter tool.” The tool reads from the device graphics subsystem (gwsi), which it can’t access on the VVD, so it produces a 0-byte file or stalls.

Here’s the correct approach for each target:

  • Physical Fire TV Stick - gwsi-tool-screenshooter is the supported tool and works as documented:
vega exec vda shell gwsi-tool-screenshooter /tmp/test.png
vega exec vda pull /tmp/test.png

screenshot_base64 = driver.get_screenshot_as_base64()
(Per the docs, don't capture DRM content with this command.)

Thanks for helping us improve the Vega platform.

Warm regards,
Aishwarya

5

Thanks, that clears it up. We had followed older replies here (topics 20196 and 27750) that suggested the tool for the VVD. Two small suggestions: could the tool exit with an error on the VVD instead of writing a 0-byte file or hanging? And could the note in the VDA reference link to the Appium screenshot docs?

6

Hi @Fortemate,

Glad that cleared things up! Both suggestions make sense - failing fast with a clear error on the VVD instead of writing a 0-byte file or hanging, and cross-linking the Appium screenshot docs from the VDA reference. I’ll pass them both on to the team as feedback.

Thanks again for the detailed repro and the thoughtful suggestions - they genuinely help us improve the platform.

Warm regards,
Aishwarya