> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tandemn.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

> Fix common Tandemn setup and job submission issues.

Start with connectivity. Most first-run issues happen before the job reaches the orchestration layer.

## `tandemn check` fails

Check the server URL:

```bash theme={null}
echo $TD_SERVER_URL
```

Then confirm the CLI can reach the server from the same terminal session:

```bash theme={null}
tandemn check
```

If it still fails:

* Confirm the server is running.
* Confirm the server URL includes the correct host and port.
* Confirm your network can reach the server.
* Confirm any firewall or VPN rules allow the connection.
* Confirm `TD_API_KEY` is set if the server requires authentication.

## Control plane does not start

On the server host, check Python and setup output:

```bash theme={null}
python --version
sky check
```

Confirm Redis is running if you use chunked execution:

```bash theme={null}
docker run -d -p 6379:6379 redis
```

## A job is rejected

Common causes:

* The model is not supported by the deployment.
* The input file path is wrong.
* The prompt file is not valid JSONL.
* The requested SLO is outside the conventions used by your deployment.
* The cluster does not currently have compatible capacity.
* `S3_UPLOAD_BUCKET` is unset or points at a bucket the control plane cannot write to.
* AWS credentials lack EC2, S3, or service quota permissions.
* The performance database is missing and the advisor is unavailable.

## A prompt file fails

Validate that each line is a complete JSON object.

```json theme={null}
{"custom_id":"req-1","method":"POST","url":"/v1/chat/completions","body":{"model":"placeholder","messages":[{"role":"user","content":"Hello"}],"max_tokens":256}}
```

Avoid trailing commas and multi-line JSON objects in JSONL files.

## Still blocked

Send your administrator:

* The command you ran
* The value of `TD_SERVER_URL`, without secrets
* The model name
* The first few non-sensitive lines of the JSONL file
* The error message from the CLI