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

# Troubleshooting

### Port Access Permission

If you can't find the port when launching the Ubuntu HMI:

* Method 1: Add the current user to the `dialout` group

  ```bash theme={null}
  sudo usermod -a -G dialout $USER
  ```

  After execution, apply the permissions:

  * Current terminal only: `newgrp dialout`
  * System-wide: `sudo reboot`

* Method 2: Launch the HMI with sudo
  ```bash theme={null}
  sudo wuji-hand-hmi
  ```

### Display Scaling Warning

If a display scaling warning appears during startup, the system display scaling ratio is greater than 100%. Adjust the display scaling to 100% (1:1) in your system settings, then restart the HMI.


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