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SFTP flow fails for some of the files (the others work perfectly fine)

Hello!

I have a problem with a flow in Power Automate. There is a flow which every time a file is created in OneDrive's directory replicates this file to a remote server via SFTP connection.

This flow processes a few hundreds files every day. For most of them the flow works without any issue, it normally takes < 1 second to process the file. However, every day there are 2-3-5 cases when the file transfer fails:

The error message says "BadGateway" with the status 502, error comment is "An established connection was aborted by the server." That is strange because those files are similar to hundreds of other files which go through to the final destination without a problem.

We had some problems with file name's length (>256 symbols or something like this) some time ago, but after that case we implemented shortening of file name, these files we're having problems with have the same file name length as other files (nearly 190 symbols normally). The file size is normal as well, about 30-50 kb.

On Power Automate side we dont have much more details regarding why this is happening, apart from the error code I've mentioned. Whats even more strange, our network admin told me this 502 error code is related to HTTP protocol, not SFTP, so its unclear why do we even get this. Likely this error is whats being passed to us from some intermediate servers on Microsoft side, but basically this is a black box for us.

With this in mind, I wanted to ask community for help, because I've ran out of options. What can be the reason that 95% of files every day are being transferred via SFTP protocol successfully, but 5% of files fail? What can be the difference between those files, to cause a problem when uploading to a server?

Thank you!

Hi @bermakov

Not sure if you got an answer but I wanted to share some thoughts

1. I notice that in the Failure you show that there was a flow triggered, I dont want to say a minute apart as its possible it was not a full minute

This and the process itself that copies the files there, can keep the files locked which would for sure cause this issue as well as things like Name, or File Size.

My suggestion, would be to add the proper Error Handling, so that it can be captured, and immediately retried, or put a small delay in.

I cannot see your flow so I have to essentially make up this for you but think on it like this

Flow Triggers

Add a variable (boolean) call it FileCopied, set to false

Add a variable (int) call it RetryCount set to 0

Add a variable (int) call it MaxRetries set to 5 (or whatever you want).

Add a Do Until, make it run until either

MaxRetries > 5 Or FileCopied = true

Now inside the do until you need to create a Try Catch

Add a Scope call it Try

Add two scopes in Parallel below it

rename one to Success

rename other to Failed

In the Try scope, ass your code to try to copy the file

Set the RunAfter Configuration for the Success Scope to.. well Successs :-)

Set the RunAfter Configuration for the Failed to Failed, Skipped, TimeOut

Inside the Success scope add a Set variable

Set the FileCopied to true

Ignore the RetryCount

Inside the Failed scope add 1 Increment Variable

Since FileCopied was defaulted to False we dont need to set that there

instead, use the Increment Variable on the RetryCount and add 1

Doing this will cause it to retry 5 times, where-in the FileCopied would be False and the RetryCount would be 6. This would cause it to kick you out of the DoUntil

Since in the Success you set FileCopied to true, it would kick you out.

Outside of both scopes, but after the Do Until add a Condition

In the Condition check if

FileCopied is equal to true (the expression not the string)

In the Yes, you can use Terminate Action set to Success

in the No, you can use Terminate Action set to Failed

You can even log a message if you want, but you would know for a fact it tried 5 times and exitted because thats your logic.

Failures will happen, we just need to work around them.

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