UiPath’s Terminal Session connectivity with IBM Mainframe is intermittent

Hi Community,

Would like to seek your kind help in the following issue we are having.


My organisation had been having connectivity problems between UiPath’s Terminal activity session and our IBM Mainframe.The connection is intermittent and perhaps out of 10 times we run the workflow, connection to mainframe will fail 3~4x with error message ‘There was an error connecting to terminal. Error code: Error’ (Refer to logs below)

Information on Issue:

a. We are using Rocket Passport PC to Host terminal emulator (Version 64bits coupled with IBM Mainframe (TN3270 / TN3270E)

b. In Terminal session, we are specifying the below details.

EHLL dll path: C:\Users<UserID>\AppData\Local\Microsoft\AppV\Client\Integration\B836D810-0BBC-4D70-A381-8D0411EF1E34\Root\VFS\ProgramFilesX64\PASSPORT\PassHll32.dll


c. I have also extracted the logs here:

Source: Terminal Session
Message: There was an error connecting to terminal. Error code: Error
Exception Type: System.Exception
An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
System.Exception: There was an error connecting to terminal. Error code: Error
   at UiPath.Terminal.Activities.TerminalSession.EndExecute(NativeActivityContext context, IAsyncResult result)
   at UiPath.Terminal.Activities.AsyncNativeActivity.BookmarkResumptionCallback(NativeActivityContext context, Bookmark bookmark, Object value)
   at System.Activities.Runtime.BookmarkCallbackWrapper.Invoke(NativeActivityContext context, Bookmark bookmark, Object value)
   at System.Activities.Runtime.BookmarkWorkItem.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)

Appreciate if anyone could help on this. We had been trying to find out what was the root cause but have not had much inroads. Thanks in advance!!



Can I check if you have now resolved this Issue ?

We are also experiencing interimittent connectivity with TN3270 plus

1 Like

Hi @mark.cook,

I have not been able to find a exact solution to solve this at the moment unfortunately.

Do let me know if you manage to find one too!



Sorry for very late answer here.
Truth be told, there are way too many possible reasons for intermittent connectivity issue.
We’ve been working on simplifying the situation in order to increase the chances for stability.

Via EHLL, you are dealing with 3 actors (Backend <-> Terminal Application <-> UiPath) out of which we can really control just one.

Since Terminal Activities 2.0.0, UiPath embeds (and has control over) its own terminal (integrating a well established commercial SDK).
In this paradigm, we only have 2 actors (Backend <-> UiPath) removing enough possible instability factors (and it was observed and demonstrated as such in our tests and real life projects)

So I highly recommend switching from EHLL API to the Direct Connection provider (Backend IP Address and port are needed but you will find those in IBMs terminal app configuration).

While doing this, other parameters you will need to care are: the encoding (has to be the IBM EBCDIC encoding corresponding to the language), Terminal ID (the default would work in most cases) and SSL/TLS flag. These are again items that should be available by examining the Session/Connection parameters in the existing Terminal Application (be it IBM Personal Communications or other application).

(Hope this will help in related searches as this post seems to come on top for intermittent connectivity issues).

1 Like