web
You’re offline. This is a read only version of the page.
close
Skip to main content
Community site session details

Community site session details

Session Id :
Power Automate - Using Connectors
Answered

Error when connecting Power Automate to SFTP on AWS Transfer Family: Server HMAC algorithm not found

(1) ShareShare
ReportReport
Posted on by 11

Hi,

 

I'm attempting to use Microsoft Power Automate to connect to an AWS SFTP instance (Transfer Family). The SFTP host is working in that I can connect to it using the Linux sftp command line client.

 

When attempting to connect using MS PA, I get this error: Server HMAC algorithm not found

 

The AWS log shows this: 

{    

"activity-type": "KEX_FAILURE",    

"source-ip": "xxxx",    

"resource-arn": "arn:aws:transfer:regions-xxxxxx:server/xxxx",    

"message": "no matching host key type found",    

"kex": "ssh-rsa,ssh-dss,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521"

}

 

Does anyone know what the problem might be?

 

I have the same question (0)
  • theblisster Profile Picture
    5 on at
    Re: Error when connecting Power Automate to SFTP on AWS Transfer Family: Server HMAC algorithm not found

    Exact same problem here! please help!

  • Verified answer
    stephen1 Profile Picture
    11 on at
    Re: Error when connecting Power Automate to SFTP on AWS Transfer Family: Server HMAC algorithm not found

    It seems the problem was with the key. The private key needs to start with -----BEGIN RSA PRIVATE KEY----- (not -----BEGIN OPENSSH PRIVATE KEY-----

    ) for this to work. 

     

    To create a key like this, follow these two steps:

     

    1. ssh-keygen -t rsa -b 4096 -f my_rsa_key
    2. ssh-keygen -p -f my_rsa_key -m pem (then use that key to connect using power automate private key)
  • Yugendiran Profile Picture
    2 on at
    Re: Error when connecting Power Automate to SFTP on AWS Transfer Family: Server HMAC algorithm not found

    Exact same problem. Any solution?

  • tgaki Profile Picture
    2 on at
    Re: Error when connecting Power Automate to SFTP on AWS Transfer Family: Server HMAC algorithm not found

    We were having similar issues with a customer using Power Automate.  After some digging into both sides of the issue, I found that the Transfer Security Policy on the AWS Transfer Family configuration was too new for Power Automate to connect.  Unfortunately it looks like there's absolutely no control over this from the client perspective with Power Automate, so the only solution for this to work is to downgrade the Transfer Security Policy to at least "TransferSecurityPolicy-2020-06" on the Transfer Family SFTP instance.

     

    Additionally, stephen1's response is correct as well in that the key needs to be in RSA PRIVATE KEY format, not OPENSSH.

Under review

Thank you for your reply! To ensure a great experience for everyone, your content is awaiting approval by our Community Managers. Please check back later.

Helpful resources

Quick Links

Coming soon: forum hierarchy changes

In our never-ending quest to improve we are simplifying the forum hierarchy…

Chiara Carbone – Community Spotlight

We are honored to recognize Chiara Carbone as our Community Spotlight for November…

Leaderboard > Power Automate

#1
Tomac Profile Picture

Tomac 544 Moderator

#2
Michael E. Gernaey Profile Picture

Michael E. Gernaey 482 Super User 2025 Season 2

#3
chiaraalina Profile Picture

chiaraalina 287

Last 30 days Overall leaderboard

Featured topics