---
title: "Media Servers Troubleshooting"
description: "Troubleshooting guide for Jellyfin media server issues including GPU transcoding failures, driver mismatches, container startup problems, network connectivity, Roku/Apple TV playback, and emergency recovery."
type: troubleshooting
domain: media-servers
tags: [jellyfin, nvidia, gpu, transcoding, docker, roku, troubleshooting, recovery]
---

# Media Servers - Troubleshooting Guide

## Common Issues and Solutions

### GPU Transcoding Problems

#### GPU Not Detected in Container
**Symptoms**:
- Jellyfin shows "No hardware acceleration available"
- Transcoding falls back to CPU (slow performance)
- Container logs show NVIDIA device not found

**Diagnosis**:
```bash
# Check GPU accessibility from container
docker exec jellyfin nvidia-smi

# Verify NVIDIA runtime is configured
docker info | grep -i nvidia

# Check container GPU configuration
docker inspect jellyfin | grep -i gpu
```

**Solutions**:
1. **Verify NVIDIA Container Runtime**:
   ```bash
   # On host
   nvidia-smi  # Should work

   # Install nvidia-container-toolkit if missing
   sudo apt install nvidia-container-toolkit
   sudo systemctl restart docker
   ```

2. **Fix Docker Compose Configuration**:
   ```yaml
   services:
     jellyfin:
       deploy:
         resources:
           reservations:
             devices:
               - driver: nvidia
                 count: all
                 capabilities: [gpu]
   ```

3. **Restart Container**:
   ```bash
   docker compose down
   docker compose up -d
   ```

#### Driver/Library Version Mismatch
**Symptoms**:
- `nvidia-smi` fails with "driver/library version mismatch"
- Container won't start with NVML error
- GPU monitoring shows "Restart failed"

**Cause**: NVIDIA driver updated on host but kernel modules not reloaded

**Solution**:
```bash
# Check host GPU status
nvidia-smi  # Will fail with mismatch error

# Reboot required to reload kernel modules
sudo reboot

# After reboot, verify
nvidia-smi
docker exec jellyfin nvidia-smi
```

**Prevention**:
- See `/media-servers/jellyfin-ubuntu-manticore.md` NVIDIA Driver Management section
- Hold driver packages to prevent auto-updates
- Monitor for updates weekly via automated checks

#### Transcoding Starts Then Fails
**Symptoms**:
- Playback begins then stops
- Jellyfin logs show ffmpeg errors
- GPU memory errors in logs

**Diagnosis**:
```bash
# Check GPU memory usage
nvidia-smi

# Check for concurrent GPU users (Tdarr, other containers)
docker ps | grep -E "tdarr|jellyfin"

# Check Jellyfin transcode logs
docker logs jellyfin 2>&1 | grep -i transcode | tail -50
```

**Solutions**:
1. **GPU Resource Conflict**: If Tdarr is using GPU, pause transcoding or limit concurrent jobs
2. **Insufficient GPU Memory**:
   ```bash
   # Check GPU memory
   nvidia-smi --query-gpu=memory.used,memory.total --format=csv

   # Reduce Jellyfin transcode resolution or bitrate
   ```
3. **Codec Not Supported**: Verify codec is supported by GPU encoder
   ```bash
   # Check available encoders
   docker exec jellyfin ffmpeg -encoders 2>/dev/null | grep nvenc
   ```

### Container Startup Issues

#### Container Won't Start After Update
**Symptoms**:
- Container exits immediately after `docker compose up -d`
- Exit code indicates error (non-zero)

**Diagnosis**:
```bash
# Check container logs
docker logs jellyfin

# Check exit code
docker inspect jellyfin | grep ExitCode

# Try starting in foreground for detailed output
docker compose up
```

**Common Causes & Solutions**:

1. **Permission Issues**:
   ```bash
   # Fix ownership of config/cache directories
   sudo chown -R 1000:1000 ~/docker/jellyfin/config
   sudo chown -R 1000:1000 /mnt/NV2/jellyfin-cache
   ```

2. **Port Already in Use**:
   ```bash
   # Check if port 8096 is in use
   sudo lsof -i :8096

   # Kill conflicting process or change Jellyfin port
   ```

3. **Volume Mount Failures**:
   ```bash
   # Verify all mount points exist and are accessible
   ls -la ~/docker/jellyfin/config
   ls -la /mnt/NV2/jellyfin-cache
   mount | grep /mnt/truenas/media
   ```

#### Container Stuck in "Restarting" Loop
**Symptoms**:
- Docker shows container constantly restarting
- Brief uptime then crash

**Diagnosis**:
```bash
# Watch restart behavior
docker stats jellyfin

# Check logs for crash reason
docker logs jellyfin --tail 200

# Check resource limits
docker inspect jellyfin | grep -A 10 Resources
```

**Solutions**:
1. **Database Corruption**:
   ```bash
   # Stop container
   docker stop jellyfin

   # Backup database
   cp ~/docker/jellyfin/config/data/library.db{,.bak}

   # Try recovery
   sqlite3 ~/docker/jellyfin/config/data/library.db "PRAGMA integrity_check;"
   ```

2. **Configuration File Issue**:
   ```bash
   # Rename config to force regeneration
   mv ~/docker/jellyfin/config/system.xml{,.bak}

   # Restart container
   docker compose up -d
   ```

### Network & Connectivity

#### Can't Access Web Interface
**Symptoms**:
- http://10.10.0.226:8096 not responding
- Connection timeout or refused

**Diagnosis**:
```bash
# Check if container is running
docker ps | grep jellyfin

# Check port binding
docker port jellyfin

# Test local connectivity
curl -I http://localhost:8096
curl -I http://10.10.0.226:8096

# Check firewall
sudo ufw status | grep 8096
```

**Solutions**:
1. **Container Not Running**: Start container
   ```bash
   docker compose up -d
   ```

2. **Port Not Bound Correctly**:
   ```yaml
   # Fix docker-compose.yml
   ports:
     - "8096:8096"  # Not "0.0.0.0:8096:8096" on some systems
   ```

3. **Firewall Blocking**:
   ```bash
   sudo ufw allow 8096/tcp
   ```

#### Client Discovery Not Working
**Symptoms**:
- Jellyfin apps can't auto-discover server
- Must manually enter IP address

**Diagnosis**:
```bash
# Check UDP discovery port
docker port jellyfin | grep 7359

# Verify UDP traffic allowed
sudo ufw status | grep 7359
```

**Solution**:
```bash
# Ensure UDP port exposed
# In docker-compose.yml:
ports:
  - "7359:7359/udp"

# Allow in firewall
sudo ufw allow 7359/udp
```

### Performance Issues

#### Slow Transcoding Performance
**Symptoms**:
- Buffering during playback
- High CPU usage despite GPU available
- Transcoding slower than real-time

**Diagnosis**:
```bash
# Check if GPU transcoding is actually being used
nvidia-smi dmon -s u -c 5  # Monitor GPU usage

# Check Jellyfin Dashboard > Playback for active transcodes

# Verify hardware accel is enabled in Jellyfin settings
```

**Solutions**:
1. **Hardware Acceleration Not Enabled**:
   - Dashboard → Playback → Transcoding
   - Select "NVIDIA NVENC"
   - Enable desired codecs

2. **GPU Busy with Other Tasks**:
   ```bash
   # Check what else is using GPU
   nvidia-smi

   # Pause Tdarr if running
   docker stop tdarr-node-gpu
   ```

3. **Cache on Slow Storage**:
   ```bash
   # Verify cache is on NVMe, not network storage
   docker inspect jellyfin | grep -A 5 cache

   # Should be /mnt/NV2/jellyfin-cache (NVMe)
   # NOT /mnt/truenas/... (network)
   ```

#### High Memory Usage
**Symptoms**:
- Jellyfin using excessive RAM
- Server becomes unresponsive
- OOM (Out of Memory) errors

**Diagnosis**:
```bash
# Check memory usage
docker stats jellyfin

# Check for memory leaks in logs
docker logs jellyfin | grep -i memory
```

**Solutions**:
1. **Set Memory Limits**:
   ```yaml
   # In docker-compose.yml
   deploy:
     resources:
       limits:
         memory: 4G
   ```

2. **Reduce Transcode Throttle**:
   - Dashboard → Playback
   - Lower "Throttle Transcodes" value

3. **Clear Transcode Cache**:
   ```bash
   # Stop container
   docker stop jellyfin

   # Clear transcode cache
   rm -rf /mnt/NV2/jellyfin-cache/transcodes/*

   # Start container
   docker start jellyfin
   ```

### Playback Problems

#### Playback Stuttering Despite Good Network
**Symptoms**:
- Video plays but stutters/buffers frequently
- Network speed is adequate
- Direct play works, transcoding stutters

**Solutions**:
1. **Check Transcode Quality Settings**:
   - Lower bitrate in client settings
   - Reduce resolution if needed

2. **Verify GPU Transcoding Active**:
   ```bash
   # While playing, check GPU usage
   nvidia-smi dmon -s u
   # Should show encoder (enc) usage
   ```

3. **Check Storage I/O**:
   ```bash
   # Monitor disk I/O during playback
   iostat -x 2 5
   ```

#### Roku/Apple TV Playback Timeout (TrueHD/DTS-HD MA Audio)
**Symptoms**:
- Playback hangs at "Loading" for 20-30 seconds then fails on Roku
- Jellyfin logs show forced transcoding with subtitle extraction delay
- Works fine on web browser or mobile clients

**Root Cause**: File has incompatible default audio (TrueHD, DTS-HD MA, Opus) AND a default SRT subtitle. Jellyfin must transcode audio AND burn-in subtitles over HLS. The 27-second subtitle extraction delay causes Roku client timeout.

**Incompatible Audio Codecs** (Roku/Apple TV):
| Codec | Status |
|-------|--------|
| AC3 (Dolby Digital) | Native playback |
| AAC | Native playback |
| EAC3 (Dolby Digital+) | Native playback |
| TrueHD | Requires transcode |
| DTS / DTS-HD MA | Requires transcode |
| Opus | Requires transcode |

**Immediate Fix** (per-file with mkvpropedit):
```bash
# Clear subtitle default, set compatible audio as default
mkvprobedit "file.mkv" \
  --edit track:s1 --set flag-default=0 \
  --edit track:a1 --set flag-default=0 \
  --edit track:a3 --set flag-default=1
```

**Systemic Fix**: Tdarr flow plugins `ensAC3str` (adds AC3 stereo fallback) and `clrSubDef` (clears non-forced subtitle defaults) — see `tdarr/CONTEXT.md`

#### Audio/Video Sync Issues
**Symptoms**:
- Audio and video out of sync during playback

**Solutions**:
1. **Enable Audio Passthrough** (if supported by client)
2. **Update ffmpeg** in container (usually handled by Jellyfin updates)
3. **Try Different Transcode Settings**:
   - Disable subtitle burn-in if not needed
   - Change audio codec settings

### Monitoring & Alerts

#### GPU Monitor Alerts Not Working
**Symptoms**:
- No Discord notifications when GPU issues occur
- Monitoring script seems to run but no alerts

**Diagnosis**:
```bash
# Test Discord webhook
python3 /home/cal/scripts/jellyfin_gpu_monitor.py --discord-test

# Check monitoring logs
tail -f /home/cal/logs/jellyfin-gpu-monitor.log

# Verify cron job is running
crontab -l | grep jellyfin_gpu
```

**Solutions**:
1. **Webhook URL Invalid**:
   - Verify webhook URL in script
   - Test with curl: `curl -X POST <webhook_url>`

2. **Script Permissions**:
   ```bash
   chmod +x /home/cal/scripts/jellyfin_gpu_monitor.py
   ```

3. **Cron Environment Issues**:
   ```bash
   # Test script manually
   /usr/bin/python3 /home/cal/scripts/jellyfin_gpu_monitor.py --check --discord-alerts
   ```

## Emergency Recovery Procedures

### Complete System Recovery

#### Jellyfin Won't Start (All Else Failed)
1. **Stop Container**:
   ```bash
   docker stop jellyfin
   docker rm jellyfin
   ```

2. **Backup Configuration**:
   ```bash
   cp -r ~/docker/jellyfin/config ~/docker/jellyfin/config.backup.$(date +%Y%m%d)
   ```

3. **Pull Fresh Image**:
   ```bash
   docker pull jellyfin/jellyfin:latest
   ```

4. **Recreate Container**:
   ```bash
   cd ~/docker/jellyfin
   docker compose up -d
   ```

5. **Restore Settings** (if needed):
   - Copy specific config files from backup
   - Don't restore corrupt database

#### GPU Completely Broken
1. **Verify Host GPU**:
   ```bash
   # If nvidia-smi fails with driver mismatch
   sudo reboot
   ```

2. **Remove GPU Access** (temporary workaround):
   ```yaml
   # Comment out GPU sections in docker-compose.yml
   # CPU transcoding only until GPU fixed
   ```

3. **Reinstall NVIDIA Drivers** (if reboot doesn't help):
   ```bash
   # Unhold packages
   sudo apt-mark unhold nvidia-driver-570

   # Reinstall
   sudo apt remove --purge nvidia-*
   sudo apt install nvidia-driver-570
   sudo reboot

   # Re-hold after working
   sudo apt-mark hold nvidia-driver-570
   ```

## Preventive Maintenance

### Regular Checks (Weekly)
```bash
# Check GPU health
nvidia-smi

# Verify Jellyfin accessible
curl -I http://10.10.0.226:8096

# Check disk space (cache can grow large)
df -h /mnt/NV2
df -h ~/docker/jellyfin/config

# Review logs for errors
docker logs jellyfin --since 7d | grep -i error
```

### Monthly Tasks
```bash
# Update Jellyfin
cd ~/docker/jellyfin
docker compose pull
docker compose up -d

# Clean old transcodes
find /mnt/NV2/jellyfin-cache/transcodes/ -type f -mtime +7 -delete

# Backup configuration
tar -czf ~/jellyfin-config-backup-$(date +%Y%m%d).tar.gz ~/docker/jellyfin/config/
```

### Before Major Changes
- Create snapshot if on Proxmox
- Backup full config directory
- Test on non-production instance if possible
- Document current working configuration

## Roku Buffering on Weak WiFi — Client Bitrate Cap (2026-03-26)

**Severity:** Low — single device, non-critical viewing location

**Problem:** Roku in a far corner of the house with poor WiFi signal was buffering/failing to play videos. Content was not being transcoded down to accommodate the limited bandwidth.

**Root Cause:** Jellyfin does not dynamically adapt bitrate mid-stream (no HLS ABR like Netflix). The server's `RemoteClientBitrateLimit` was set to `0` (unlimited), and LAN clients are treated as "local" anyway so that setting wouldn't apply. The Roku Jellyfin app was requesting full-quality streams that exceeded the WiFi throughput.

**Fix:** Set **Max Streaming Bitrate** in the Jellyfin Roku app settings (Settings > Playback) to a lower value (4-8 Mbps). This forces the server to transcode down via NVENC before sending. No server-side changes needed.

**Lesson:** For bandwidth-constrained clients, the client-side bitrate setting is the first lever to pull. For a server-enforced cap that survives app resets, create a dedicated Jellyfin user for that device and set a per-user bitrate limit in Dashboard > Users > Playback. The `RemoteClientBitrateLimit` in system.xml only applies to clients Jellyfin considers "remote" — LAN devices are always "local."

---

## PGS Subtitle Default Flags Causing Roku Playback Hang (2026-04-01)

**Severity:** Medium — affects all Roku/Apple TV clients attempting to play remuxes with PGS subtitles

**Problem:** Playback on Roku hangs at "Loading" and stops at 0 ms. Jellyfin logs show ffmpeg extracting all subtitle streams (including PGS) from the full-length movie before playback can begin. User Staci reported Jurassic Park (1993) taking forever to start on the living room Roku.

**Root Cause:** PGS (hdmv_pgs_subtitle) tracks flagged as `default` in MKV files cause the Roku client to auto-select them. Roku can't decode PGS natively, so Jellyfin must burn them in — triggering a full subtitle extraction pass and video transcode before any data reaches the client. 178 out of ~400 movies in the library had this flag set, mostly remuxes that predate the Tdarr `clrSubDef` flow plugin.

**Fix:**
1. **Batch fix (existing library):** Wrote `fix-pgs-defaults.sh` — scans all MKVs with `mkvmerge -J`, finds PGS tracks with `default_track: true`, clears via `mkvpropedit --edit track:N --set flag-default=0`. Key gotcha: mkvpropedit uses 1-indexed track numbers (`track_id + 1`), NOT `track:=ID` (which matches by UID). Script is on manticore at `/tmp/fix-pgs-defaults.sh`. Fixed 178 files, no re-encoding needed.
2. **Going forward (Tdarr):** The flow already has a "Clear Subtitle Default Flags" custom function plugin (`clrSubDef`) that clears default disposition on non-forced subtitle tracks during transcoding. New files processed by Tdarr are handled automatically.

**Lesson:** Remux files from automated downloaders almost always have PGS defaults set. Any bulk import of remuxes should be followed by a PGS default flag sweep. The CIFS media mount on manticore is read-only inside the Jellyfin container — mkvpropedit must run from the host against `/mnt/truenas/media/Movies`.

## Related Documentation
- **Setup Guide**: `/media-servers/jellyfin-ubuntu-manticore.md`
- **NVIDIA Driver Management**: See jellyfin-ubuntu-manticore.md
- **GPU Monitoring**: `/monitoring/scripts/CONTEXT.md`
- **Technology Overview**: `/media-servers/CONTEXT.md`
- **Main Instructions**: `/CLAUDE.md`

## Support Resources
- **Jellyfin Docs**: https://jellyfin.org/docs/
- **NVIDIA Container Toolkit**: https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/
- **Discord Monitoring**: See `/monitoring/scripts/jellyfin_gpu_monitor.py`