ERROR: "XCOMN0322E Cannot access file server: <reason>" connecting to a network drive

Products

• XCOM Data Transport - Windows

Issue/Introduction

A remotely-initiated transfer that specifies a network file name in the UNC format (\\server\share\folder\file.ext) requires XCOM to establish a connection with the file server. This connection may fail so the transfer will fail with message "XCOMN0322E Cannot access file server: <reason>", where "<reason>" is the text associated to the Windows error code received by the connection attempt.

It has been observed sometimes that a transfer fails at the first attempt and works fine when retried immediately with the the same exact parameters.

Environment

XCOM™ Data Transport® for Windows

Cause

XCOM establishes the connection to the file server by invoking function WNetAddConnection2() provided by the Windows API so that Windows manages the connection establishment.

Using a tool like Wireshark to trace the TCP/IP traffic between the Windows box and the file server for one of these cases revealed that, when the connection failed, Windows was not passing the domain name to the file server even though the transfer was running under the security scope of a domain userid. Windows passed the domain name when the connection succeeded.

Resolution

Fix LU07574 USING DOMAIN NAME AS PART OF USERID WHEN ACCESSING UNC PATHS improves the situation by two changes:

1. Pass the domain name as well as the username to function WNetAddConnection2() (in the format "domain\user") when the transfer request specifies DOMAIN= parameter so that the use of the domain name to establish the connection does not depend on a decision from Windows.
2. Make the error  XCOMN0322E Cannot access file server: <reason>  a retriable one so that XCOM may retry the transfer if requested to do so in the transfer parameters. This way a connection that failed at the first attempt may have further chances to succeed without manual intervention.

The fix sets the XCOM cumulative maintenance level to r11.6 SP03 22100.  This fix is included in all newer releases as well as version 12.0.