# Troubleshooting
## Prometheus Connection Refused
Check that Prometheus is running and reachable:
```bash
curl http://localhost:9090/-/healthy
```
If you are using the demo stack, the Prometheus port is `19090`:
```bash
curl http://localhost:19090/-/healthy
```
## No Data Appears
Prometheus may need a few scrape intervals before data is available. Wait 10 to 15 seconds and force a refresh with `r`.
Also confirm that the dashboard queries match labels in your Prometheus server:
```bash
grafatui --prometheus-url http://localhost:9090 --grafana-json ./dashboard.json --var job=prometheus
```
## Dashboard Variables Do Not Match
Override variables explicitly with `--var`:
```bash
grafatui --grafana-json ./dashboard.json --var instance=localhost:9090
```
If a Grafana dashboard uses multi-select formatting modifiers such as `${var:csv}` or `${var:regex}`, check the [compatibility matrix](grafana-compatibility.md). Not every Grafana interpolation mode is implemented.
## Demo Port Conflict
The demo Prometheus service uses host port `19090`. If that port is already in use, edit `examples/demo/docker-compose.yml` and run Grafatui with the updated URL.
## Export Directory Problems
Set an explicit export directory:
```bash
grafatui --export-dir ./grafatui-exports
```
Make sure the directory is writable by your current user.