Error in HPLIP -- Unable to create io-slave

[shmu26]

When adding a file to a fax to be sent, from the dialogue box of the HPLIP Fax Utility,
I get the following error:
Unable to create io-slave. Can not create socket for launching io-slave for protocol 'file'.

I tried changing the KDE default file manager to Thunar, but HPLIP still seems to be using Dolphin. I think the issue might be with Dolphin, so if I could get HPLIP to use a different file manager, it might help.

It is still possible to fax a file by opening it in an application, then print, then select the fax printer. However, only one file can be sent at a time that way.

HPLIP 3.20.5, device manager version 15.0 (Qt4)

Operating System: Kubuntu 20.04
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.4.0-33-generic
OS Type: 64-bit
Processors: 8 × Intel® Core™ i7-9700 CPU @ 3.00GHz
Memory: 15.5 GiB of RAM

[jglen490]

Have you run

hp-check

against your current setup?

It may reveal some driver/module issues. I don't know if that will fix your problem, since I don't use my HP for faxing, but I do know that the hp-check utility has helped me to fix printing issues with my setup.

[shmu26]

Have you run

hp-check

against your current setup?

It may reveal some driver/module issues. I don't know if that will fix your problem, since I don't use my HP for faxing, but I do know that the hp-check utility has helped me to fix printing issues with my setup.

No errors found

[shmu26]

I installed XFCE desktop on the same system, with the same user account, for testing purposes, and I don't see the issue in XFCE. So it definitely seems to be KDE-related.

[claydoh]

For whatever reason, HP's software is not accessing KDE's (or more likely Qt's) file chooser (it is not Dolphin, though it looks similar) - which of course would not normally be used in a Qtk envirionment such as Xfce. The issue is figuring out why, especially since this specific bug does not look to have been reported anywhere I can find.

I have seen this exact same error message in the past, here on KFN, but it was for a version of the KDE Partition manager, and was a known bug in that particular piece of software at the time.
I'd try and check things myself, but my ancient 12+ year old photosmart died a few months back