Error - Server aborted session: Unknown authentication method


When attempting to make a transfer with ascp, the following error message appears:

Server aborted session: Unknown authentication method

This error occurs when an invalid token is supplied for the transfer, and the transfer is being made to a transfer server version 3.6.0 or greater.

In previous versions, transfer servers would not fail due to invalid tokens (such as with a sample token), but in 3.6.0 and greater an error message is thrown.


If you have a custom application that makes use of tokens for transfers, ensure valid tokens are being supplied.

# ascp -W "valid_token" ...

The -W option of ascp defines the token string for the transfer. If you don’t have a need for tokens in your transfers, remove this option from your ascp command.

An alternative to setting your token in the ascp command itself is to set it in the environment variable ASPERA_SCP_TOKEN before making a transfer:

Linux or Mac
# export ASPERA_SCP_TOKEN=token_string

> set ASPERA_SCP_TOKEN=token_string
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