Connect via salesforce authentication node

I am using Knime Analytics platform version 4.6.1 build 27.07. and I am using Microsoft Windows 10 Enterprise. To be able to connect to a Salesforce database I use the Salesforce Authentication Node. In the configuration I use the option:

OAuth interactive Authentication (via browser) and Memory (credentials kept in memory).

There are days when this way works very well. Unfortunately there are days when this way causes an error. Could not start callback server: Failed to bind to

Somehow the port seems to be blocked. With netstat -a -n -o this port is not shown. Unfortunately, since I only have a limited user account, I can’t tell which programs are listed here.

At this point I can’t get any further. Also a reboot does not help. The error remains. After the first error message comes a second one: “A authentication with Salesforce is already in progress. Wait until the other authentication process is done or cancel it.”
I can’t cancel the authentication process because the “cancel” button is covered by the error message.

Does anyone have an idea?

Hello @TimTim36 ,

Welcome to the Forum!

Thank you for your very detailed description and all the preliminary trouble shooting what you did before.

KNIME uses 51778 during the Salesforce Authentication. This port number is fixed in our code so you can not change it via any settings at the moment. Sorry for the inconvenience!

Regarding to that you are not able to cancel the authentication process because the button is covered by the error message, could you please share a print screen of it?


Hello Dora_gcs,

are there any known interactions, applications that also use this port? Sometimes oauth works fine.

I use edge as a browser and have already cleared the cache several times. But that seems to have no effect.
To me it looks like something is timed to access the ports and probably the open applications are also affected. Is there perhaps a process that breaks all connections after x hours? At some point KNIME seems to cure this error, by itself.
Enclosed the screenshot.

Thanks and with greetings

Hello @TimTim36 ,

Thank you for the screenshots.
To be honest I was not able to get exactly the same error msg as you got, I got different ones but I always managed to hit the OK button and the error msg was gone, no any other Cancel button hidden behind the error msg. Are you sure if you hit the OK button does not the error msg go?

Regarding to the port, 51778 is a high port number so it could be freely use by any other application, we really can not say which application on the world is using this port.
What we can say is that within KNIME there are not any other function which uses this port.

If you have an other instance of KNIME using the same port at the same time they could block each other.


Hi Dora GCS,

the error message can be closed, that is correct. That is not the problem. My problem is that I can’t close the connection setup in oauth, because exactly this dialog has a Cancel button, but you can’t reach it, because the OK to close the error message also closes the dialog from the connection setup at the same time. So currently I can’t reach the dialog from the oauth anymore and therefore I can’t cancel it either.

Thanks for your help