> For the complete documentation index, see [llms.txt](https://kb.howsci.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kb.howsci.com/troubleshooting/problems-communicating-with-the-host.md).

# 主机通信错误

有的在线数据库需要账号和密码，详见[访问收费数据库](/online-databases/access-restricted-databases.md)