Presence of Elmo .DS causes TWAIN to crash?

[twainuser123]

Hi,

I have spent many hours trying to debug this issue but was unable to come up with a solution.
Some of our customers have a Elmo TWAIN driver installed. However, the strange thing is that the presence of this driver in “C:/windows/twain_32” causes TWAIN to crash upon unloading from the application.
We can rename it to “ElmoVHO.ds.1” (on our own machine) to get rid of the problem, but we can’t do this in the customer’s machine.

I can reproduce the problem on my machine simply by copying the attached folder into my “C:/windows/twain_32”

With the latest TWAIN DSM (2.1), our application crashes with no exception.
However, with the older TWAIN 1.7 DSM dll, our application only crashes if we touch the Elmo source with a MSG_GETDEFAULT/MSG_GETNEXT to get its TW_IDENTITY. If we simply use MSG_GETDEFAULT and Elmo was not selected, the problem does not occur. Strangely, if we force the TWAIN user select dialog to be shown, the application only crashes if the user selects the Elmo source, regardless of whether we do a MSG_GETNEXT on it.

Does anybody have any ideas? I couldn’t find any bugs in our application and the debugger showed the crash occurring when the TWAIN DSM tried to unload the Elmo .ds.
Feel free to ask any questions for clarification as I have explored many options.

[Adam]

Hi,

Some questions about your crash issue:

1. I’m not quite sure when you get the crash. Does it happen on selecting Elmo TWAIN driver as the current source, or on scanning from this specific driver?

2. Is it a web application or desktop? Did you try getting a dump file to troubleshoot the problem?

__________________
Adam
Dynamsoft: version control | TWAIN SDK

[twainuser123]

Hi Adam,

Thanks for the response.

1. The crash actually happens after the program is done running. Everything works correctly, except the TWAIN DLL crashes upon unloading the elmo ds.
We don’t actually scan from the Elmo device; we use a different scanner (i.e. epson scanner).
The crash will happen if we do a MSG_GETDEFAULT or MSG_GETNEXT and grab the TW_IDENTITY for the elmo source.
Strangely, it seems that the crash does not occur if we ask TWAIN to display some kind of UI window (be it “Select Scanner” or the TWAIN acquisition interface for the scanner that is actually used to scan).

2. It is a desktop application. We did get a windows dump file, but all it told us was that TWAIN DLL crashed upon unloading the elmo ds.

I hope this makes sense. I think you would be able to reproduce this as well.

[Adam]

Hi,

It reminds me of an issue our team once had. Crash happens when scanning from some scanners without showing the user interface (it’s a web application though). I’m not sure if it’s the same problem you are experiencing. Our team was able to solve the problem by configuring the thread. Hope it helps.

__________________
Adam
Dynamsoft: version control | TWAIN SDK

[twainuser123]

Thanks. This does help because it seems we aren’t isolated in this issue.

What do you mean by configuring the thread? If possible, could you please give me more details on this so we can work around this issue?

[Author]

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