Recent changes to 403: Cached device list causes issue

#403 Cached device list causes issue

Jeffrey Ratcliffe — Wed, 28 Sep 2022 07:55:52 -0000

Apologies for the late response.

The device list should be cached at the point that you enable the cache, and then also every time the list is updated.

Disabling the cache does not clear it. Would it make sense to clear it when the cache is disabled? Are there situations where the user disables the cache to do something (i.e. plug in a new device).

I don't think so, as even with the cache enabled, you can still select "Rescan for devices" from the device drop-down. And indeed this should have solved your problem immediately.

Hence, I see two improvement I could make here:

If gscan2pdf sees the "Error opening device" error, it could offer to rescan for devices.
Disabling the cache should clear it.

What do you think?

#403 Cached device list causes issue

Jan — Mon, 11 Jul 2022 11:41:40 -0000

edit: the issue reappeared.

The exact error message is:
Error opening device: opening device 'smfp:usb; 04e8;343d;Z4OQBAFC201175B': Operation not supported

followed by this when trying to start the scan nevertheless:
gscan2pdf: must open device before starting scan

When I disable the caching, the scanner is detected and scanning works. But I want to keep caching enabled, so I reenable the setting and after restarting gscan2pdf, the same error message appears.

I think I fixed it now: Disable cache device list, research scanner, enable caching, research again. THEN you may exit gscan2pdf. Otherwise the old cache with the broken device will be reused.

Should disabling caching clear the cache?

Cached device list causes issue

Jan — Mon, 11 Jul 2022 11:32:36 -0000

Hi, I recently reinstalled my Linux distro and after that gscan2pdf would not work anymore. My scanner would show up but when trying to start a scan, it would complain that the operation to start the scanner is not permitted. Searching again for the scanner returned "no devices found".

I was able to fix this by disabling "cache device list" in the preference menu which allowed me to restart the device search. Apparently the device ID had changed due to the reinstallation of my OS. Maybe there is a smart way to automate this process? E.g. throw away the device list if search fails or a device cannot be found? Or this can be included as a help-note when searching a scanner fails?

Thanks