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 Aspera Connect in windows version 4.2+ needs "Key passphrase" and "Password"

feng chen's profile image
feng chen posted Thu April 02, 2026 10:15 AM
Hi Community,
I have encountered some issues over the past two days. Approximately 4 years ago, I successfully used Aspera Connect on Windows to download SRA data from the ENA database. However, in the past two days, when using Aspera Connect Windows version 4.2+, I found that after entering the command line, I am prompted to enter "Key passphrase" and "Password".
I have checked the Aspera and ENA official websites and learned that it seems necessary to configure the "ASPERA_SCP_PASS" environment variable. However, even after doing this, I still cannot download successfully.
Therefore, I would like to know:
  1. What is causing this issue?
  2. How should I resolve this problem?
Additionally, I have downloaded Aspera for Desktop, but frustratingly, I have no idea how to use it. I would greatly appreciate it if someone could provide a user manual for Aspera for Desktop.
Thank you very much for your help!
Best regards,

Jose Gomez's profile image
Jose Gomez posted Thu April 02, 2026 07:38 PM

Hi,

It seems this is referring to the instructions at https://ena-docs.readthedocs.io/en/latest/retrieval/file-download.html#using-aspera. Trying to download the example public file from that page works for me with the following command line on Windows with the latest Connect version:

C:\Users\MyUser> set ASPERA_SCP_PASS=xxxx

C:\Users\MyUser> "c:\Program Files\IBM\Aspera Connect\bin\ascp" -i "c:\Program Files\IBM\Aspera Connect\etc\aspera_tokenauth_id_rsa" -P 33001 -l 300m era-fasp@fasp.sra.ebi.ac.uk:vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz .
ERR164407.fastq.gz                            100%   72MB 38.0Mb/s    00:13
Completed: 74523K bytes transferred in 13 seconds
 (44817K bits/sec), in 1 file.

The value of ASPERA_SCP_PASS would be set replacing xxx for the actual secret for the RSA key. With the correct value, if you are still seeing errors please post the error you are seeing.

With regards to the documentation for Aspera for Desktop, it is available at https://www.ibm.com/docs/en/aspera-for-desktop/1.0.x?topic=getting-started

Laurent Martin's profile image
Laurent Martin posted Fri April 03, 2026 05:03 PM

If you have ascli you can get the xxxx with:

ascli conf ascp info --fields=uuid --show-secrets=yes

or you can get the path to the unlocked common private key with (best option):

ascli conf ascp info --fields=ssh_private_rsa

You can get ascli binary for Linux (GLIBC 2.30+) in the Release section: 

https://github.com/IBM/aspera-cli/releases/tag/v4.25.4



For ENA access, you can do like this:

ascli conf preset update era --url=ssh://fasp.sra.ebi.ac.uk:33001 --username=era-fasp --ssh-keys=$(ascli conf ascp info --fields=ssh_private_rsa) --ts=@json:'{"target_rate_kbps":300000}'

and then browse:

ascli -Pera server br /

and download:

ascli -Pera server download vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz

Note that IBM provides two similarly named client apps: Aspera Desktop Client and Aspera for Desktop.
The later is kind of a successor of the earlier.

You can use both to connect to ENA, like in ascli above, use the following information:

hostname: fasp.sra.ebi.ac.uk

username: era-fasp

ssh-key: Use the file specified by: ascli conf ascp info --fields=ssh_private_rsa

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