- "Cannot open TWAIN source"
- Canon scanners like the "CanoScan LiDE 60"
What does not hep:
- Updating/reinstalling CanoScan toolbox or drivers
- Trying other USB ports
- Shorten your "PATH" environment variable. If the resulting variable is "too long", the TWAIN error will occur. After shortening the path, scanning will immediatly work (no restart required.)
(Thanks to “Graf_d” from this thread for providing the solution)