OpenVPN will display the error message "AUTH: Received control message: AUTH_FAILED" in the connection log if the OpenVPN server rejects a connection during the authentication stage. While this is typically the result of an incorrect username and/or password, an OpenVPN server may also reject a VPN connection during the authentication stage for other reasons as well.

It should be noted that in some instances seeing an "AUTH_FAILED" message in the log is normal and does not indicate a problem. For example, if using dynamic two-factor authentication (where the OpenVPN server prompts you for additional credentials, such as a one-time password) an AUTH_FAILED message in the log is normal and part of the process. It should only be considered a problem if the VPN connection is unable to connect.

If you are unable to connect your VPN Connection, and you're seeing an "AUTH: Received control message: AUTH_FAILED" message in the connection log, then in the first instance you should contact your VPN Provider. An AUTH_FAILED message comes from the OpenVPN server and indicates it is rejecting your authentication attempt. Only your VPN Provider can tell you exactly why this is occurring (they should be able to check their server logs). If you are unsure of who your VPN Provider is please see How Do I Find Out Who My VPN Provider Is?

Common causes of an AUTH_FAILED message include:

• The OpenVPN server is rejecting the username and/or password you're using. Make sure that the details you're entering are correct, and that your account with your VPN Provider is active and allowed to authenticate. It is recommended you get in contact with your VPN Provider in this instance to check your account is still valid and the username and password being used are correct.

• The OpenVPN server is rejecting your connection attempt as the two-factor credentials being used are invalid or missing. If your VPN connection requires that you authenticate using two-factor authentication (such as a one-time password, authenticator code, etc.) make sure it is being entered, it is correct, and it's not expired. If you're unsure whether you need to enter two-factor credentials, please get in contact with your VPN Provider.

• The OpenVPN is rejecting your connection attempt as it limits the number of active connections. Some OpenVPN servers may be configured to enforce a limit on number of connections that can be active at the same time. If this enforcement is done in an authentication script or plugin on the server, then you will receive an AUTH_FAILED message if the server believes there are too many active connections. This could be enforced on a per-user basis (for example only a single connection is allowed per user) or server wide (for example the server may only allow a total of 10 connections at a time among all users). In some cases an OpenVPN server may not immediately notice a VPN connection has been disconnected, and so you may need to wait several minutes before attempting to connect. Please get in contact with your VPN Provider to check whether any connection limits are being reached.

• The OpenVPN server is rejecting your connection's certificate. This can be the case if the OpenVPN server accepts the certificate for the initial connection, but then rejects it in an authentication script or plugin. You should contact your VPN Provider to see whether you need to update your VPN connection configuration.

• Your connection's configuration details may be incorrect or out of date. VPN Providers may periodically update their VPN servers, so you may need to download updated connections to import. You will need to get in contact with your VPN Provider to ensure your configuration details are correct and up to date.

• There is a problem with the OpenVPN server. In some cases there may be a problem with the OpenVPN server that is causing authentication attempts to fail. For example, back-end authentication systems might be down or unavailable. Please get in contact with your VPN Provider to ensure that the OpenVPN server is available and not experiencing any problems.