Download the file ps_picker.lrdevplugin.zip:
On macOS, the Edit In command in Lightroom Classic opens a copy of Photoshop from a back-up location.
For example, an external hard drive back-up created using Carbon Cloner, SuperDuper! or Time Machine. This can result in the following behaviors:
Download the file ps_picker.lrdevplugin.zip:
Download
Double-click the ps_picker.lrdevplugin.zip file to unzip it.
Launch Lightroom Classic and select File > Plug-In Manager.
Click Add to install the plug-in.
Select File > Plug-In Extras > Select Photoshop for Edit in Photoshop.
Click Select and navigate to the version of Photoshop running on your main (boot) drive.
Click OK to dismiss the dialog.
Relaunch Lightroom Classic for the change to take affect.
Sign in to your account