A service cannot be started

The most common reasons why the SFTP Server or Web Administration service fails to start:

• The default port is already in use by another application — port 22 for the SFTP Server, port 8880 for the Web Administration.
• The service user does not have the required read/write permissions to the configuration directory.

A user cannot connect

• Firewall: Nine times out of ten, it's the firewall. Check that the relevant port is open in the local Windows firewall and in any network firewall or IDS between the client and the server.
• NAT: If the server is behind NAT, the client must connect to the external IP address, not the internal one. For FTP passive mode, make sure the external address is set correctly and the data port range is open in the firewall.
• Account lockout: The user may be locked out after too many failed login attempts. Check the user's status in the Web Administration or using burusftp user inspect. See account lockout for details.

Configuration changes have no effect

Restart the SFTP Server service after modifying config.yaml. Most changes are not picked up automatically.

Remote user cannot write to their folder

Make sure the service user (or impersonated Windows account, when enabled) has write access to user folders.

Web Administration cannot change any setting

Make sure the Web Administration service user has read/write access to the configuration directory.

Unable to access user database file error

Make sure the current Windows user has read/write access to the configuration directory, or run the command as an administrator.

YamlDotNet.Core.SemanticErrorException error

YAML is picky about formatting. Make sure your configuration files are properly indented — always use 2 spaces (never tabs). See the YAML Wikipedia page for the gory details.