FTP error messages explained

Valid for Web Hosting and Hosting for WordPress.

If your SFTP/FTPS program cannot establish a connection to your webspace, there can have various causes. Therefore, the programs usually display an error message with the corresponding error code (if possible). We have compiled an overview of the most common error messages with solutions for you below.

Note

Typing mishaps when entering login details are a common source of error. Often it is only small careless mistakes that prevent success. You should therefore pay attention to typing errors such as transposed letters and — especially with usernames and passwords — to correct capitalisation.

Error message from the FTP program	Cause	Solution
421 Too many connections	The maximum number of simultaneous connections has been reached.	Terminate any FTP sessions that are no longer needed. Some FTP programs, such as FileZilla, can use multiple connections per FTP session. Check your settings and, if necessary, reduce the number of simultaneous connections/transfers. Background information: In shared hosting environments, the maximum number of simultaneous connections is limited to prevent potential disruption to other users. Unfortunately, we cannot provide an exact number, as this depends on various factors that can influence each other. We recommend keeping the number in the low single digits to prevent potential complications.
The specified host is unknown. Connection closed.	The FTP server (host) cannot be reached or is unknown.	Please check your entry. For Web Hosting, the server name must match the format homexxxxxxxxx.1and1-data.host or accessxxxxxxxxx.webspace-data.io. Example: home123456789.1and1-data.host or access123456789.webspace-data.io. If the FTP server is specified correctly, your FTP program may not be compatible with the .host extension as part of the server name. You can still use the program by configuring a custom subdomain as an alternative server name.
Error 530 - Login incorrect	Authentication failed due to incorrect username or password.	Please check your input. Please note that access is only possible using your personal FTP username. You can find more information about your login credentials here. Forgotten your password?Then simply set a new password in your IONOS account.
425 Unable to build data connection: Connection refused	The FTP connection was established, but no data could be exchanged.	A common cause is using the FTP program in active mode, which can lead to problems with network components such as a firewall or router. Enable passive mode in your FTP program's settings.
550 Permission denied	This error occurs whenever you try to create folders or files in a directory where you do not have the necessary permissions.	Check the file and folder permissions on your webspace or server.
Connection timed out after 20 seconds of inactivity / Failed to connect to the server.	The FTP server (host) cannot be reached or is unknown.	Please check the FTP server you entered. Note that for IONOS web hosting, you must use your personal FTP server name from your IONOS account instead of your domain name. Example: access12345678.webspace-data.io You can find more information about your login credentials here