This message is produced by an OpenSSH (or Sun SSH) server if it receives more failed authentication attempts than it is willing to tolerate.
This can easily happen if you are using Pageant and have a large number of keys loaded into it, since these servers count each offer of a public key as an authentication attempt. This can be worked around by specifying the key that's required for the authentication in the PuTTY configuration (see
section 4.21.8
); PuTTY will ignore any other keys Pageant may have, but will ask Pageant to do the
authentication, so that you don't have to type your passphrase.
On the server, this can be worked around by disabling public-key authentication or (for Sun SSH only) by increasing MaxAuthTries in sshd_config.
10.5 ‘Out of memory’
This occurs when PuTTY tries to allocate more memory than the system can give it. This may happen for genuine reasons: if the computer really has run out of memory, or if you have configured an extremely large number of lines of scrollback in your terminal. PuTTY is not able to recover from running out of memory; it will terminate immediately after giving this error.
However, this error can also occur when memory is not running out at all, because PuTTY receives data in the wrong format. In SSH-2 and also in SFTP, the server sends the length of each message before the message itself; so PuTTY will receive the length, try to allocate space for the message, and then receive the rest of the message. If the length PuTTY receives is garbage, it will try to allocate a ridiculous amount of memory, and will terminate with an ‘Out of memory’ error.
This can happen in SSH-2, if PuTTY and the server have not enabled encryption in the same way (see
question A.7.5
in the FAQ).
Some versions of OpenSSH have a known problem with this: see
question A.7.16
.
This can also happen in PSCP or PSFTP, if your login scripts on the server generate output: the client program will be expecting an SFTP message starting with a length, and if it receives some text from your login scripts instead it will try to interpret them as a message length. See
question A.7.6
for details of this.
10.6 ‘Internal error’, ‘Internal fault’, ‘Assertion failed’
Any error beginning with the word ‘Internal’ should never occur. If it does, there is a bug in PuTTY by definition; please see
appendix B
and report it to us.
Similarly, any error message starting with ‘Assertion failed’ is a bug in PuTTY. Please report it to us, and include the exact text from the error message box.
10.7 ‘Unable to use this private key file’, ‘Couldn't load private key’, ‘Key is of wrong type’
Various forms of this error are printed in the PuTTY window, or written to the PuTTY Event Log (see
section 3.1.3.1
) when trying
public-key authentication, or given by Pageant when trying to load a private key.
If you see one of these messages, it often indicates that you've tried to load a key of an inappropriate type into PuTTY, Plink, PSCP, PSFTP, or Pageant.
You may have specified a key that's inappropriate for the connection you're making. The SSH-1 and SSH-2 protocols require different private key formats, and a SSH-1 key can't be used for a SSH-2 connection (or vice versa).
Alternatively, you may have tried to load an SSH-2 key in a ‘foreign’ format (OpenSSH or ssh.com) directly into one of the PuTTY tools, in which case you need to import it into PuTTY's native format (*.PPK) using PuTTYgen - see
section 8.2.12
.
10.8 ‘Server refused our public key’ or ‘Key refused’
Various forms of this error are printed in the PuTTY window, or written to the PuTTY Event Log (see
section 3.1.3.1
) when trying
public-key authentication.