Comment 53 for bug 478761

The 'failed to start scanner: invalid argument' error message seems rather non-specific, and by association I think this bug discussion overall seems rather non-specific. I can intermittently replicate this error message by plugging my Fujitsu ScanSnap S500 into an over-loaded USB hub. lsusb still shows it, but scanimage -L gives the "no scanners were identified" error, and of course xsane gives the "failed to start scanner: invalid argument" error. Unplugging the scanner and plugging it into a different USB port fixes the issue.

I think what the original poster described seems like a hardware-specific issue, and maybe this should be separated out into one bug per scanner model, or at least better described in the bug title.