Unable to open twain source - canoscan lide 500f. the driver is installed in the twain_32 folder correctly. the canoscan toolbox 4.9 is in the program (x86) folder). i also have arc soft photostudio and it cannot find it either (twain error). removing arc soft app did not fix this either. can someone think of anything else?. In the bottom panel, scroll until you find the variable named path. select this one and then hit the edit… button to bring up the edit system variable dialog. in the variable value text box, scroll all the way to the right and then add in the path c:windowstwain_32cnq4803 that was determined earlier.. It worked before but when i connect usb on windows 7 and open canoscan toolbox (or press the scan button on the scanner which opens the same software) it keeps telling me that its unable to acquire twain source..
I tried everything to solve the problem of "cannot find twain source".. uninstalled,reinstalled, tried canon downloads,bought driiver repair software, everything. never did find a solution ,but would not give up coz the damn thing used to work and still does if you test through control panel. i now use the scanner by opening windows publisher, insert picture,insert from scanner, then save as. Canon scanner – unable to open twain source. unable to open twain source please check connection then re-start toolbox. finally, i restart the canonscan toolbox. now my scanner works without any issues and the same should be true with your scanner. newer post. older post.. If not, go to c:windowstwain_32, and see if you have a folder similar to cnql60 they copy the full path of the folder into clipboard click windows' start button, then search "environment", then.