I receive the message: "The extension could not be loaded because it was not properly signed."

https://youtu.be/0YuJdeIBwGM

Try this video.

Some Mac-specific notes that I had kept when this was common back in the day for plug-ins (not extensions)... Posted just in case it helps somebody.

Workaround for old plug-ins not created for macOS 10.15

For older plug-ins that are not notarized, customers with Admin user privileges can remove the quarantine flag by using the following Terminal.app command if the plug-in is installed in the Photoshop application plug-ins folder:

sudo xattr -r -d com.apple.quarantine /Applications/Adobe\ Photoshop\ 2019/Plug-ins/<plug-in-name>

Or, use the following command if the plug-in is installed in the shared Creative Cloud plug-ins folder:

sudo xattr -r -d com.apple.quarantine /Library/Application\ Support/Adobe/Plug-Ins/CC/<plug-in-name>

You would obviously need to change the file path and or plug-in name as required.

thi is don in one click

make file .reg from .text and double  click and don

mean copy this down text and past text document and save .reg file 

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Adobe\CSXS.11]
"LogLevel"="1"
"PlayerDebugMode"="1"

I found a solution for photoshop CC 2020. Close your Photoshop. Copy and Paste the following into a text file, save it as reg file (literally change the .txt in the back into .reg and save). Then double click on it to run. Open Photoshop and extension should load now.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Adobe\CSXS.6]
"PlayerDebugMode"="1"
[HKEY_CURRENT_USER\Software\Adobe\CSXS.7]
"PlayerDebugMode"="1"
[HKEY_CURRENT_USER\Software\Adobe\CSXS.8]
"PlayerDebugMode"="1"
[HKEY_CURRENT_USER\Software\Adobe\CSXS.9]
"PlayerDebugMode"="1"
[HKEY_CURRENT_USER\Software\Adobe\CSXS.10]
"PlayerDebugMode"="1"

This solution worked for me on photoshop cc 2018

Open Terminal, type:

defaults write com.adobe.CSXS.8 PlayerDebugMode 1 

Then press return

exit

Then press return

Good luck

I install the Adobe Photoshop cc 14,but when i open it ,i have the same problem.maybe it's version of china or just free ,so i can't fix the problem by using tips given by you ,but who can help?

Simple Copy paste the Folder into "C:\Program Files (x86)\Common Files\Adobe\CEP\extensions\"

if folder CEP and extension not found create one

I'm on Mac OS 10.11.16 using Adobe Photoshop 2017, having the same problem.

Tried a number of the above solutions

     - Deleting prefs using Command-Option-Shift on launch

     - Preferences > Enable Generator / Allow Extensions to Connect To the Internet / Load Extension Panels

     - Tested using one of Davide Barranca's extensions from GitHub - undavide/PS-Panels-Boilerplate: Boilerplate code and examples for Adobe Photoshop CC (and following) HTML Panel…​

Getting the same error in all cases.

win - HKEY_CURRENT_USER/Software/Adobe/CSXS.7

add String PlayerDebugMode=1

mac Terminal

defaults write com.adobe.CSXS.7 PlayerDebugMode 1

exit

Guys Just change CSXS.6 to CSXS.7

This solution worked for me on photoshop cc 2015.5

Open Terminal, type:

defaults write com.adobe.CSXS.7 PlayerDebugMode 1 

Then press return

Good luck