magical xml file mystery.

File attributes? and web interfaces.
We have a custom application that generates an xml file download to the user workstation.  This file is then uploaded to our vendor web site to place purchases.
For User A, this is no problem. It works properly from any browser installed on his PC.
For User B, the upload fails to execute, either without comment, or sometimes complaining of an xml file error.  Does not elaborate on what the error is, just says there is one.  (gotta love that.)  It does not matter what browser, the error is the same.

Sounds fairly straight forward right? Why bother you guys with this?  This is where it gets interesting.

If user A generates the file, and sends it to user B via email attachment, User B cannot upload it. Going the other way, the file generated by user B cannot be uploaded by user A if it is sent via email attachment, BUT it WILL upload if it is sent via Slack instant message!  This fact was a total random discovery, and in fact we then found that if user B generates the file, sends it to himself via slack, he can then upload it!

I have exhaustively gone through all the browser settings, versions for windows, browser, updates, Java, .net, anti-virus even default xml viewer and all match.

When user A comes down and logs in on the problem machine, the problem exists for him as well, so a user profile problem is not a probable cause.

I have two files in front of me, One that will work, one that won't, and the only thing different is the name.
Same size
same date
same attributes
same owner
same security
same content (even the same white space in the content!)

I have run a hash generator against the file before and after sending it through Slack, and the hash is different.

So what is changing in the file?
And why would only one PC have the problem?

The other thing in front of me is a head shaped depression in the wall.

Ideas?
LVL 3
Bill HerdeOwnerAsked:
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aikimarkCommented:
Have you run a diff/compare utility against the two XML files?
Bill HerdeOwnerAuthor Commented:
Yes.  Ran an xml compare tool which found no differences in the content.  The only thing that showed a difference was a hash generating tool. This really should not be a problem if the content is the same, but something is going on.
aikimarkCommented:
Please post an example of two files that have different hash values but aren't 'different'
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BigRatCommented:
Very probably an encoding problem. I look forward to analysing the two files.
Gerwin Jansen, EE MVETopic Advisor Commented:
Try zipping both files before sending, do both come across?

If you use 7zip to zip the files, you can check the CRC _in_ the archive before/after transfer. Give files the same name on both systems before zipping.
Bill HerdeOwnerAuthor Commented:
Let me see if there is anything in there I'm not allowed to have public, and I will get to that on Monday.
Bill HerdeOwnerAuthor Commented:
aikimarkCommented:
There are three more bytes in the bad version than the good version.  My first hypothesis is that these are the BOM bytes.
aikimarkCommented:
Notepad++ supports my hypothesis, indicating the good one is UTF-8 w/o BOM and the bad one is UTF-8

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Bill HerdeOwnerAuthor Commented:
I can forward that to my programmers, but why would only one PC be doing this?
aikimarkCommented:
Software and OS levels?
Configuration settings?
Different utilities/routines/libraries?
Bill HerdeOwnerAuthor Commented:
So far I have found no differences on the workstations. (see above) I will scour the browser settings for anything UTF encoding related.
Gerwin Jansen, EE MVETopic Advisor Commented:
Exactly how is the file being uploaded to the vendors site? That is what must be different one the 'bad' workstation.
Bill HerdeOwnerAuthor Commented:
The upload is done via the vendor web page.  It has the controls in handy buttons.  Yes, they have a new version of this page, which would explain why it became an issue.  User is going to lunch soon and I can take over his desk to look for settings for upload.
aikimarkCommented:
This may be a phased roll-out of the vendor site features or an A/B test by the vendor, where one user has a different UX
Gerwin Jansen, EE MVETopic Advisor Commented:
I thought it was system not user related?
BigRatCommented:
In my experience most of the (L)unix based systems and utilities (node. for example) do not like UFT8 files with a BOM and cause a parsing error.
Bill HerdeOwnerAuthor Commented:
This is a new system the vendor is bringing online, but our system generates the file.  With many converters available we can at least convert and upload now, and I have our programmers looking to see if it can be removed before we get it downloaded.  

I still am unable to figure out how one user is able to upload!  I am not finding any setting or registry hack that would set a preference when downloading a file, but it is getting pretty clear that something is happening on his PC to make it save without BOM. I am able to perform the download portion from my desk, and now that I know what to be looking for, I confirmed that I also get UTF-8 with BOM, but user A does not!
Bill HerdeOwnerAuthor Commented:
Getting the fix on this is gone to the programmer/web folks.  The problem is identified and a work around found to keep us going until they fix it.

Why it works for one guy will remain a mystery.  (If I do find it, I will add a comment.)

Thanks for the help.
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