Troubleshoot SSH Errors

Thunder Compute gives indie developers, researchers, and data-scientists low-cost cloud GPUs in a few clicks. Our CLI (tnr) and VS Code extension wrap SSH setup, key management, and port-forwarding for you—see the Quick-Start guide for a full walkthrough.

When you run tnr connect, the tool SSHs into your instance automatically. If something goes wrong, you might see errors such as:

• Bad permissions – “Try removing permissions for user: \OWNER RIGHTS (S-1-3-4) on file C:\Users<your_username>.ssh\config.”
• Error reading SSH protocol banner (often means the instance is out of memory and the SSH handshake cannot complete).
• Key authentication failed (your SSH key is outdated or misconfigured).

Follow the steps below to fix the problem.

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1. Restart the Instance

A quick restart clears many transient issues:

tnr stop
tnr start

Wait about a minute, then try tnr connect again.

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2. Test a Manual SSH Connection

Get a more detailed error message by bypassing tnr connect:

ssh tnr-0

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3. Fix Common Issues

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A. Out-of-Memory

If you see Error reading SSH protocol banner, the instance may have run out of RAM. Wait a few seconds and retry. For a permanent fix, launch an instance with more resources:

tnr create --vcpus 8

Tip: 16–32 vCPUs generally provide enough memory for most ML workloads.

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B. Permissions Problems

# Run PowerShell as Administrator
icacls "$env:USERPROFILE\.ssh\config" /reset
icacls "$env:USERPROFILE\.ssh\config" /inheritance:r
Rename-Item -Path "$env:USERPROFILE\.ssh\config" -NewName 'config.old'

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C. Corrupted Known-Hosts or Thunder Compute Locks

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Known-Hosts

Rename-Item -Path "$env:USERPROFILE\.ssh\known_hosts" -NewName 'known_hosts.old'

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Thunder Compute Locks & Keys

Remove-Item -Recurse -Force "$env:USERPROFILE\.thunder\locks"
Remove-Item -Recurse -Force "$env:USERPROFILE\.thunder\keys"

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4. Reinstall the Thunder Compute CLI or VS Code Extension

If the steps above do not resolve the error, reinstalling the tooling often does:

1. Remove the existing CLI or extension.
2. Download the latest installer from Thunder Compute download.
3. Re-run tnr login followed by tnr connect.

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5. Still Having Issues?

Open a ticket in our Discord support channel with the exact error output, and we will get you unblocked fast.

Happy troubleshooting!