Hardware decoding fails in Flatpak on Linux Mint 22.3 / AMD Radeon R5; Moonlight falls back to software decoding

Describe the bug
After updating Moonlight to version 6.1.0, hardware decoding stopped working on my Linux Mint 22.3 system. The previous Moonlight version did not show this error on the same laptop and setup. Since then, Moonlight reports that no functioning hardware accelerated video decoder is available and falls back to software decoding. paste.txt github

On Linux Mint 22.3 Xfce (X11) with an ASUS X555QG laptop using an AMD Radeon R5 Graphics (Carrizo) GPU, Moonlight 6.1.0 Flatpak reports that no functioning hardware accelerated video decoder is available. The app launches, but hardware decoding fails for H.264 and Moonlight falls back to FFmpeg/software decoding. The logs also show repeated VAAPI and VDPAU initialization failures. ppl-ai-file-upload.s3.amazonaws

Steps to reproduce

1. Install Moonlight as Flatpak from Flathub.
2. Launch it with flatpak run com.moonlight_stream.Moonlight.
3. Open a host and start streaming.
4. Observe the hardware decoding error and software fallback. ppl-ai-file-upload.s3.amazonaws

Screenshots
I attached screenshots showing Moonlight settings, system information, and the error dialog stating that no hardware accelerated video decoder was detected. ppl-ai-file-upload.s3.amazonaws

Affected games
I reproduced the issue while trying to stream from my host PC KernelOS-PC. The problem appears to be client-side and occurs before game-specific behavior can be isolated. ppl-ai-file-upload.s3.amazonaws

Other Moonlight clients
I did not fully verify iOS or Android in this report, so I cannot confirm whether the issue occurs there. The failure is reproducible on the Linux Mint Flatpak client. ppl-ai-file-upload.s3.amazonaws

Moonlight settings

• Video codec: H.264.
• Decoder: Automatic.
• Resolution tested: 1080p and lower.
• FPS: 30.
• Bitrate: initially around 54.5 Mbps, later reduced during troubleshooting.
• HDR and AV1 were not the intended path for this GPU. ppl-ai-file-upload.s3.amazonaws

Logs to attach

Use this short block in the issue or attach the terminal output:

vainfo confirms H.264 VA-API support on the host:
VAProfileH264ConstrainedBaseline : VAEntrypointVLD
VAProfileH264Main               : VAEntrypointVLD
VAProfileH264High               : VAEntrypointVLD

Moonlight Flatpak logs show:
- Failed to initialize VAAPI -1
- Failed to open VDPAU backend libvdpauradeonsi.so
- Failed to create VDPAU context
- Using generic FFmpeg hwaccel backend
- FFmpeg-based video decoder chosen

That log summary is accurate and supported by the output you shared. ppl-ai-file-upload.s3.amazonaws

Additional context

I originally installed Moonlight to match my system’s Linux/X11 and AMD GPU setup, and that setup worked before the 6.1.0 update. The new failure appears to be linked to the update rather than a new system installation problem.

I already tried installing vainfo, mesa-va-drivers, va-driver-all, vdpau-driver-all, and org.freedesktop.Platform.GL.default//22.08-extra. vainfo works correctly on the host system and reports H.264 hardware decode support, so the issue appears to be specific to Moonlight’s Flatpak runtime/backend interaction rather than missing host GPU support. [github](https://github.com/moonlight-stream/moonlight-docs/wiki/Fixing-Hardware-Decoding-Problems)