Lightroom Classic: Edit in PS feature doesn't work

Could you please share the complete version of Lightroom Classic you are using (available under menu Help -> System Info), and the version of Photoshop installed? Thanks.

Hi G0apher and thanks for the reply, at the moment I have Mac running:

Adobe Photoshop Version: 20.0.5 20190605.r.83 2019/06/05: 1206907  x64
Lightroom Classic version: 8.3.1

Although I have tried to use previous versions all in vain
same problem also when I tried to use the new Lightroom

"The Photoshop application launches but the image selected in Lightroom does not open in Photoshop."  is a topic in the help document at-
https://helpx.adobe.com/lightroom-classic/kb/edit-in-command-opens-copy-of-photoshop-from-back-up-dr...

Thank you so much that was a good suggestion, as I doubt that the reason for my problem is using external drives for the Library, and also the osx is installed on an external drive, but unfortunately it didn't work. 

"and also the osx is installed on an external drive"

Being curious, I searched but could find little about OS on External drive (Format needs Mac OS Extended) (I am a Windows user)
If Lightroom and Photoshop are installed on the external OS- this could be causing your problems.
Other experts may be able to add more advice on this topic.
https://helpx.adobe.com/au/lightroom-classic/system-requirements.html

So I have erased my entire hard drive disk and external SSD on which MAC OS was installed, I have reinstalled a fresh copy of MAC OS again and new LR, PS, same problem still. Edit in Photoshop will not open the image, I wonder what I can do now.

Is it possible that LR is creating smart previews automatically for my RAW FILES  that are on a different external drive and this is creating the problem???

Thanks 

So I had a breakthrough today, and I think that I have found the root of the problem, just need to identify it now with your help.

I upgraded MAC OS to High Sierra from El Capitan that I have been using since I erased my desk drives.

Old versions of LR 7.5 and PS 19.1.8 were already installed, so I did the update,

As I was updating PhotoShop, Adobe CC told me that It will keep the old PS version on the machine and will install the new one. by clicking on advanced settings there was an option that I chose to remove the old version, after Updating I was having PS 20.2.5 camera raw 10.5 and LR 8.3.1 with Camera Raw 11.3 

So I tested the Edit in Photoshop feature and it was working fine finally but it was showing this popup message:


After that I updated Photoshop Camera Raw from 10.5 to 11.3 and once again the Edit in Photoshop not working.