Logic app SFTP - SSH: each trigger opens a new connection to the sftp server

Question

Logic app SFTP - SSH: each trigger opens a new connection to the sftp server

Simone Ferrari 0

We created a new logic app (consumption) with these requirements:

it must open a connection to an sftp server
it must retrieve all the files in a folder
each file must be moved to a sharepoint folder
one moved, file must be delete by sftp folder

We added SFTP - SSH triggers/actions:

list files in a folder
get file content (infer content type = Yes)
delete file

For each action has concurrency control = Yes and Degree of parallelism = 1.

Each SFTP - SSH trigger/action open always a new connection to the sftp server, without using cached connection.

SFTP server has a ClientAliveInterval = 30 minutes and maximum 5 active connection at the same time. So at the 3rd file processed we received the issue "bad request" cause the sftp server does not accept any other connection over than 5 at the same point.

Also there is no way to set a property to close the sftp connection by the logic app.

Anyone can help me with this case?

Thank you

Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-25T18:16:41.4866667+00:00
Hello Simone Ferrari,

Thanks for reaching out, it seems you're encountering issues with the SFTP-SSH connector in your Logic App due to connection management. Each action opens a new connection, and since your SFTP server has a limit of 5 active connections, you’re exceeding this limit, resulting in the "bad request" error. Unfortunately, the SFTP-SSH connector doesn’t support reusing or caching connections. To resolve this, you can try reducing the number of concurrent actions by ensuring the degree of parallelism is set to 1.

Additionally, you can implement a delay between actions to allow idle connections to close or consider batching file operations to minimize the number of concurrent connections. If possible, adjust your SFTP server settings, such as the ClientAliveInterval or maximum allowed connections.

Alos try the below approach and check does that work for you.
Instead of handling SFTP operations directly within Logic Apps, use an Azure Function (PowerShell, Python, or .NET) that:

Opens a connection once

Fetches all files

Moves them to SharePoint

Deletes them

Closes the connection properly

The function can be triggered by Logic Apps, ensuring connection reuse and avoiding connection exhaustion.
Simone Ferrari 0 Reputation points

2025-03-27T11:02:36.9233333+00:00

Hi,
thank you for the feedback.

I've already setup the number of concurrent actions to 1, but issue still exists.

I read in another article SFTP-SSH can cache connection until 1 hour and can reuse the same connection. But it's not the behavior we have.

We cannot change the sftp server properties, logic app must move files so it takes just a few seconds to complete the task. We'd have to ask to change the ClientAliveInterval less than 1 minute.

Using an azure function means to rebuild the full solution.

It's very strange connection cannot be cache. At least there is the option to close the connection after an action? I saw it with FTP connector, but not with SFTP-SSH.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-28T19:20:28.4466667+00:00

Hello Simone Ferrari,

Just checking in to see if the above provided information is helpful and resolve the issue, if you have any further concerns, please feel free to drop them here.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-31T19:14:09.43+00:00

Hello Simone Ferrari,

We wanted to follow up on the issue you encountered. Please let us know if it's resolved or if you need further assistance.
Simone Ferrari 0 Reputation points

2025-04-28T10:10:00.1866667+00:00

Hi @Loknathsatyasaivarma Mahali
sorry for the late but we were in the middle of the go-live.

We still have the issue and we cannot redesign the solution now.

So unfortunately we have to find another option.

Thank you

2 answers

Your answer

Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-25T18:16:41.4866667+00:00

Hello Simone Ferrari,

Thanks for reaching out, it seems you're encountering issues with the SFTP-SSH connector in your Logic App due to connection management. Each action opens a new connection, and since your SFTP server has a limit of 5 active connections, you’re exceeding this limit, resulting in the "bad request" error. Unfortunately, the SFTP-SSH connector doesn’t support reusing or caching connections. To resolve this, you can try reducing the number of concurrent actions by ensuring the degree of parallelism is set to 1.

Additionally, you can implement a delay between actions to allow idle connections to close or consider batching file operations to minimize the number of concurrent connections. If possible, adjust your SFTP server settings, such as the ClientAliveInterval or maximum allowed connections.

Alos try the below approach and check does that work for you.
Instead of handling SFTP operations directly within Logic Apps, use an Azure Function (PowerShell, Python, or .NET) that:

Opens a connection once

Fetches all files

Moves them to SharePoint

Deletes them

Closes the connection properly

The function can be triggered by Logic Apps, ensuring connection reuse and avoiding connection exhaustion.
Simone Ferrari 0 Reputation points

2025-03-27T11:02:36.9233333+00:00

Hi,
thank you for the feedback.

I've already setup the number of concurrent actions to 1, but issue still exists.

I read in another article SFTP-SSH can cache connection until 1 hour and can reuse the same connection. But it's not the behavior we have.

We cannot change the sftp server properties, logic app must move files so it takes just a few seconds to complete the task. We'd have to ask to change the ClientAliveInterval less than 1 minute.

Using an azure function means to rebuild the full solution.

It's very strange connection cannot be cache. At least there is the option to close the connection after an action? I saw it with FTP connector, but not with SFTP-SSH.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-28T19:20:28.4466667+00:00

Hello Simone Ferrari,

Just checking in to see if the above provided information is helpful and resolve the issue, if you have any further concerns, please feel free to drop them here.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-03-31T19:14:09.43+00:00

Hello Simone Ferrari,

We wanted to follow up on the issue you encountered. Please let us know if it's resolved or if you need further assistance.
Simone Ferrari 0 Reputation points

2025-04-28T10:10:00.1866667+00:00

Hi @Loknathsatyasaivarma Mahali
sorry for the late but we were in the middle of the go-live.

We still have the issue and we cannot redesign the solution now.

So unfortunately we have to find another option.

Thank you

Answer 1

Hello Simone Ferrari,

The Logic Apps Consumption SFTP-SSH connector's inability to reuse or explicitly close connections, coupled with your SFTP server's connection limits, necessitates a shift to an Azure Function.

Solution: Implement an Azure Function.

The function establishes one persistent SFTP connection and it handles all SFTP actions (list, get, delete) and SharePoint transfer within that connection.
Also, the function explicitly closes the SFTP connection, preventing resource exhaustion.

This approach provides the necessary connection control, overcoming the SFTP-SSH connector's limitations. While it requires refactoring, it's the reliable way to ensure your workflow's success.

Answer 2

Sonny Gillissen 3,751 Volunteer Moderator

Hi Simone Ferrari

Thanks for reaching out on Microsoft Q&A!

As I understand you’re experiencing connection issues within your logic app while connecting to an SFTP over SSH due to persistancy.

What you could do to avoid this case is to “debatch” your files to another logic apps meaning: the logic app with the trigger executes the loop, but within the loop the file data is passed through to another logic app handling the file.

This way each subsequent logic app has it’s own one-on-one connection to the SFTP, only for that single file it should handle. Every next file is handled within another run thus another connection living on its own.

Please click ‘Accept answer’ if you think my answer is helpful. Feel free to drop additional queries in the comments below!

Kind regards,

Sonny

Simone Ferrari 0 Reputation points

2025-04-28T10:12:25.5233333+00:00

Hi @Sonny Gillissen
thank you for the answer.

Unfortunately we cannot redesign the solution now, but I think issue will not be fixed with you hint. File must be downloaded by SFTP server and also deleted by there. These 2 actions open 2 different connections.

Thank you

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Logic app SFTP - SSH: each trigger opens a new connection to the sftp server

2 answers

Your answer