scanner software for HP PSC 1315 all-in-one

[SaltCity44]

No luck.  When I tried to install the printer driver from HP Support site at the link you provided I got a warning: "Could not execute file 1310_731_EN2.smi because your security prefs allow installation of only apps from App Store & identified developers".  I went into my Security & Privacy" panel and overrode this block by clicking "open".  I then got "Following disk images couldn't be opened:  1310_731_EN2.smi".  At that point I abandoned trying to install the driver.

I then went to the link you provided to update printer firmware.  I specified "PSC 1315 All-in-One printer" (there was another

entry for PSC 1315V which I did NOT select).  I specified macOS 10.14, then downloaded "Mac Printer Driver" V5.1, rel date 10/9/19.  I then opened/launched file "HP Printer Drivers 5.1.dmg" from my downloads folder.  A window opened with an image of an opened box with yellow contents.  I got "The package was signed with a certif that has expired.  May not be authentic.  Do you want to continue with install anyway". I clicked "Continue"

I saw "Standard install on Macintosh HD", I clicked "Continue" and, after entering my password, things looked encouraging.  I saw

"Writing files... Running package scripts... Removing old files..." .  But then I got:  "System extension cannot be used...

The system extension “/Library/Extensions/hp_io_enabler_compound.kext” was installed improperly and cannot be used. Please try reinstalling it, or contact the product’s vendor for an update."

I clicked "OK", then surprisingly got "The installation was successful... The software was installed".

But when I executed Image Capture I immediately got "Software for this device is not installed... S/W is available from Apple, would you like to install it?"  I hit CANCEL and tried rebooting to see if maybe that would activate the s/w  it claimed was successfully installed. 

The reboot didn't help, I got the same msg from Image Scan.  So this time I clicked "Install" and got "Finding s/w... " then "S/W install failed".  So I'm back where I started.

I did verify I can still print, wondering if you have any additional suggestions?   Should I try downloading a driver for macOS 10.1 (the default) instead of 10.14 (my current version)?   Should I try PSC 1315V instead of PSC 1315?    Any idea how I can resolve the issue  with “/Library/Extensions/hp_io_enabler_compound.kext”?

Many thanks for your help!

[TEJ1602]

@SaltCity44

We will have to check for additional troubleshooting steps. I will write back asap.

Thanks for understanding.