Intermittent report file write error in process model

Question

Hello,
We have recently seen a couple errors we have not seen before, that are intermittent.   This occurs in the single pass entry point sequence, the first "write UUT report" step (the non-on-the-fly one).  The error message is as follows:
"An error occurred calling 'Save' in 'Report' of 'NI TestStand API 4.0'
A file with the pathname 'T:\HTC' already exists.. Error writing to file 'T:\HTC\WING\3WWE\StressTest.seq\StressTest_Report[NO_UUT_SERIAL_NUM13][3 23 37 PM][4 28 2008] - TS2.html'."
So when breaking here, and looking at Locals.ReportFilePath (which is the pointed to variable in the specifiy module of this step), it was indeed defined as:
T:\HTC\WING\3WWE\StressTest.seq\StressTest_Report[NO_UUT_SERIAL_NUM13][3 23 37 PM][4 28 2008] - TS2.html
So everything looks correct, but it thinks that "T:\HTC" is the entire path.  So the next thing I did, after much confused pondering, was go to the "variables" tab while in break, and add an extra backslash to the part following "T:\HTC" in Locals.ReportFilePath so that the path is now:
T:\HTC\\WING\3WWE\StressTest.seq\StressTest_Report[NO_UUT_SERIAL_NUM13][3 23 37 PM][4 28 2008] - TS2.html
I hit retry and it worked.  So my question is, if teststand is thinking the "\W" is an escape code, why does it work 99%+ of the time, and suddenly this weird problem? 
Thanks

Answer 1

"A file with the pathname 'T:\HTC' already exists."
This error indicates that there was a file called "T:\HTC" so the report saving code was not able to create a directory with that name. I doubt this has anything to do with backslash escaping anything since there is no expression evaluation involved and \W is not a valid backslash escapable character anyway.
Why you had a file called HTC I do not know, but I looked and that is what this error is for. The Report saving code attempts to create all of the intermediate directories if they do not already exist and if one happens to exist, but is a file and not a directory you will get this error (it is the error we get from the operating system). It is possible there is a issue with the OS where it incorrectly reports this error in some cases (perhaps with multithreaded access), but that I do not know for certain.
In searching for known OS issues I found the following:
http://support.microsoft.com/kb/q268897/
"On the other hand, an attempt to create a new C:\Development\Bin folder through the use of CreateDirectory() will fail with "ERROR_ALREADY_EXISTS". In this case, the API fails when it should succeed."
Although it does sound like it was fixed in a service pack. Are you by any chance using NTFS on Windows 2000 and are not up to date with the lastest service pack?
Also it's possibly an unknown OS bug, what OS version are you using and can you reproduce the problem in a simple case?
Also, just to be sure you might want to make sure nothing is creating a file called 'T:\HTC' in your code.
Hope this helps.
-Doug
Message Edited by dug9000 on 04-30-2008 10:58 AM