> For the complete documentation index, see [llms.txt](https://launcher-docs.netmarble.com/faq-en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://launcher-docs.netmarble.com/faq-en/launcher-launch/3.md).

# Unknown Error Alert

\* If the error occurred while downloading the launcher installation file, please refer to the \[['Unknown error (api)' when downloading](/faq-en/launcher-download/5.md)] article.

* If the problem persists even after clicking the Refresh button in the top-right corner, please restart the launcher or reboot your PC.
* If the problem persists, uninstall the launcher and reinstall it.

#### \[Checklist Before Running the Launcher]

1. Windows 10 or newer
2. Around 20 GB of free storage space

If the issue persists after the steps above, it may be a certificate issue on your PC. Please refer to the certificate check and installation steps in the \[['Server delay' notice](/faq-en/launcher-launch/8.md)] article.