Canon scanner – unable to open twain source. unable to open twain source please check connection then re-start toolbox. the problem is that the twain drivers are not within the system variables path. what i do first is open the control panel. next i click system and security.. Unable to open twain source its been working well on my new dell xps8700 running windows 10 for over 6 months. suddenly i get "unable to open twain source please check connection then re-start toolbox" unplugging and plugging the connection the computer gives the little beeps acknowledging the connection.. This looks to be a tricky one. i have two pc's running windows 7 pro with sp2. one can detect and run canon toolbox for scanning, the other does not..
