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CanoScan 9950F won't work, TWAIN problem


I am trying to make a CanoScan 9950F film scanner to work with CanoScan Toolbox, Windows 7, unsuccessfully. Installation discs are missing; drivers are installed from Canon web site.

CanoScan Toolbox fails to recognise the scanner. Its name does not appear under CanoScan Settings. The only option under Select Source is Platen, should have been Film. When I try to scan anyway, a message comes up:

"Unable to open TWAIN source. Please check connection. Then re-start Toolbox."

According to the Devise control panel, "The device is working properly." Help!



No reply so far, so please let me try to widen the question. I imagine there are, roughly three actors here. On top there is the app, CanoScan Toolbox. At the lowest level there is the 9950F driver. And in the middle there is TWAIN that intermediates between the driver at the bottom and the app on top. The problem seems to be that the connection between TWAIN and the app is broken. Anybody out there has experienced anything similar with TWAIN and any scanner app? Any other comment on this?

Thanks for joining the conversation, SigmundT!

This community is designed for your fellow Canon owners to help each other out with any problems they may encounter. If this is a time-sensitive matter, click HERE search our knowledge base or register your Canon gear HERE to access additional support options.

Thanks and have a great day!

Thank you Danny, but registration was of no use, as the 9950F is no longer supported.

One observation: The driver installer SetupSG.exe seems to do nothing. It just starts, shows a dialog box for a fraction of a second, then exits. Is there a way to see why SetupSG.exe exits so rapidly? Or better, ensure that the drivers are correctly installed?


Hi there! Although our forum community members are still welcome to provide input, please note that the 9950F has been discontinued and is no longer supported. We suggest getting in touch with the Canon Upgrade Program to avail of a discount on a newer model. You can contact them at 1-866-443-8002. To find out more about our retired products, please visit

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Finally, I believe I have come to a solution, having tried a second Windows 7 machine. The first was Windows 7 Professional, the second Home Premium. The second machine works (at least when the fast, blue, USB contacts are avoided). The Professional edition might have the same problem as Windows 10, whatever causes the trouble. At least, I now have a machine that supports the 9950F scanner.