Most likely this is either an issue because the current directory is not what you think it is, or a permissions issue because the external program runs as a Windows service which usually does not have the permissions to access network devices.

As you have not shown an SSCCE, it is quite hard to give you more concrete advice than to output all data as your program progresses to a log file and then compare the log files between a manual run and a run from the External program.

In reply to Re: Network File read not working if invoked externally by Corion
in thread Network File read not working if invoked externally by SriniK

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