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 ENA Aspera download fails with repeated 'Password:' prompt

王 王's profile image
王 王 posted Thu May 07, 2026 12:01 AM

Hi there,

I'm experiencing an issue with downloading ENA data using Aspera Connect and would greatly appreciate any insights.

I need to batch download data from ENA. A few days ago, I successfully downloaded files using Aspera Connect 4.2.19 with the following command (using the asperaweb_id_dsa.openssh file in the older version):

ascp -T -l 300m -P 33001 -i ~/.aspera/connect/etc/asperaweb_id_dsa.openssh era-fasp@fasp.sra.ebi.ac.uk:vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz ./

However, the command is now failing, only returning "Password:".

I also tried using the newer aspera_tokenauth_id_rsa key:

ascp -T -l 300m -P 33001 -i ~/.aspera/connect/etc/aspera_tokenauth_id_rsa era-fasp@fasp.sra.ebi.ac.uk:vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz ./

After entering "era-fasp" as Key passphrase:, I still get a "Password:"

What might be causing this? And how can I resolve it?

Thank you very much!

BEN FORSYTH's profile image
BEN FORSYTH posted Mon May 11, 2026 02:51 PM

Please look to use the Aspera CLI available on Github

https://github.com/IBM/aspera-cli

https://github.com/IBM/aspera-cli/blob/main/docs/README.md

To connect to remote servers that use the aspera_tokenauth_id_rsa key

Laurent Martin's profile image
Laurent Martin posted Mon May 11, 2026 03:19 PM

A quick solution is to install ascli, as Ben mentioned.

(See ENA ref: https://ena-docs.readthedocs.io/en/latest/retrieval/file-download.html#using-aspera)

Then, after installation (for example, install Ruby, then aspera-cli gem, then ascli conf ascp install:

You can get the required password like this: ascli conf ascp info --fields=uuid --show-secrets=yes

and set that password in env var: ASPERA_SCP_PASS

Alternatively, use the password-less version of the RSA key like this:

ascp -T -l 300m -P 33001 -i ~/.aspera/sdk/aspera_bypass_dsa.pem era-fasp@fasp.sra.ebi.ac.uk:vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz ./

(Note the changed path to key, the path can be displayed with : ascli conf ascp info --fields=ssh_private_rsa)

Alternatively, take advantage to use ascli directly:
ascli server --url=ssh://fasp.sra.ebi.ac.uk:33001 --username=era-fasp --ssh-keys=~/.aspera/sdk/aspera_bypass_rsa.pem download vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz --ts.target_rate_kbps=300000

You can even configure as default server:

ascli conf preset update ena --url=ssh://fasp.sra.ebi.ac.uk:33001 --username=era-fasp --ssh-keys=~/.aspera/sdk/aspera_bypass_rsa.pem

ascli conf preset set default server ena

and then browse:

ascli server br /

and download:

ascli server download vol1/fastq/ERR164/ERR164407/ERR164407.fastq.gz --ts.target_rate_kbps=300000 --to-folder=.

I recommend not to use option -T (equivalent to --ts.cipher=none), transfer options can be displayed with: ascli conf ascp spec

Regards

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