Mux plugin upload fails: video file not available from Sanity Google Storage

I understand this is a critical situation since your entire app depends on video content! The error message about sanity-scratchmux-proxy and the Google Cloud Storage URL suggests there's an issue with the video file handoff between your upload and Mux's processing system.

Based on the error pattern you're seeing, here's what's happening and how to address it:

What's Actually Happening

When you upload a video through the sanity-plugin-mux-input, the plugin facilitates uploading videos directly to Mux from within Sanity Studio. The error message indicates that Mux is unable to download the video file from a temporary storage location during processing.

Immediate Troubleshooting Steps

1. Verify Mux Service Status First, check Mux's status page to rule out any ongoing service issues on their end.

2. Check Your Mux Credentials

• Verify your Mux API Token ID and Secret Key are still valid
• Check if your Mux account has hit usage limits or quota restrictions
• Confirm the token has permissions to both read and write video and read data
• You can verify credentials in your Mux dashboard access token settings

3. Test with Different Video Files The error shows a .quicktime file. Try:

• A smaller video file (under 100MB) to rule out size/timeout issues
• A different format - MP4 with H.264 codec is most reliably supported
• Ensure the source file isn't corrupted

4. Update the Plugin Make sure you're running the latest version of the plugin:

npm update sanity-plugin-mux-input

Check the GitHub releases page for the latest version and relevant release notes.

5. Network Configuration Check If you're behind a corporate firewall or VPN:

• Try uploading from a different network
• Check for firewall rules blocking Google Cloud Storage domains
• Ensure outbound connections to Mux services are allowed

Likely Root Causes

Based on this error pattern:

1. Temporary Storage Access Issues: The file may be timing out or becoming inaccessible before Mux can download it
2. Network/Connectivity Problems: Something is preventing Mux from reaching the temporary storage location
3. File Format/Codec Issues: While QuickTime is supported, certain codecs or malformed files can cause processing failures
4. Mux Account Limits: Your Mux account may have hit storage, bandwidth, or processing limits

Getting Help - Action Required

Since this is blocking your customer completely, I recommend taking these steps immediately:

1. Contact Sanity Support Reach out to Sanity support with:

• Your project ID
• The complete error message
• When this started happening
• Whether it affects all uploads or just certain files

2. Check GitHub Issues Review the sanity-plugin-mux-input issues to see if others are experiencing similar problems. There are currently 12 open issues - check if any match your situation.

3. Contact Mux Support Since the error indicates Mux cannot download the file, reach out to Mux support as well. They can check their logs to see what's happening when they attempt to fetch your video files.

Temporary Workaround

While investigating, you could temporarily:

• Upload videos directly to Mux via their dashboard
• Manually reference the Mux asset IDs in your Sanity documents using the mux.video type
• This bypasses the plugin but allows content creation to continue

This isn't ideal, but it can keep your customer unblocked while you troubleshoot the root cause.

Important Note

The specific error mentioning sanity-scratchmux-proxy and Google Cloud Storage suggests this involves the upload pipeline infrastructure. If the troubleshooting steps above don't resolve it quickly, this may require investigation from both Sanity and Mux's support teams, as it could be an infrastructure issue rather than just a configuration problem on your end.

Given the critical nature of this issue, I'd prioritize opening support tickets with both Sanity and Mux immediately while trying the troubleshooting steps above.