The Common Extensibility Platform (CEP) suite couldn't be loaded.

For those Mac M1 users in my case the problem was that the Media Encoder installation was damaged. I was trying to fix After effects but it was until I reinstalled everything that I realized that if you install After Effects from scratch it installs 4 things automatically: Acrobat, Media Encoder, After Effects and Camera Raw which means those programas are dependencies of After Effects.
TL;DR Try reinstalling the following Acrobat, Media Encoder, After Effects and Camera Raw. If that doesn't work uninstall all adobe apps and reinstall After Effects and all remaining apps.

SOLVED: If anyone still has the problem - I tried everything and nothing works... so only thing that works is to create new user on Mac with admin permissions and use from second user. Simple.

Hola la solución fue mas sencilla de lo que esperaba, resulta que yo tenia una carpeta llamada adobe en mi documentos de la mac y tenia otras cosas dentro de ella, por lo cual le cambie el nombre y cree otra carpera llamada "adobe" completamente nueva y verifique los permisos, y a todos los usuarios le di permisos completos y listo magicamente se abrio el after effects

Hi. So i managed to solve for myself. dont know if this will work for you guys. For Mac. The instructions are as follows: 

1. uninstall after effects and media encoder. 

2. Next, uninstall creative cloud from the folder they give you called creative cloud unistaller 

3. then head over to adobe website and hit install After Effects from the website. it will give you download link so follow all the steps to download it. 

4. Creative cloud will also be downloaded along with the After Effects. note you wont have to download After Effects from the creative cloud app. since you already downloaded it from the website. 

5. once After Effects downloads launch it and it should be working without this metadata BS poping up.

hope this helps. if this works for you please show your appreciation by subscribing to my youtube channel: HEAR 2 STAY 

I tried all adviced but non of them did not work for me. 

But I find another solution 

for windows user Settings- Update and Security- Windows Security-Virus and threat protection- manage ransomware protection-Allow an app through Controlled folder access-please select after effects exe from installed win folder. and restart after effect 

you can also watch from here to

https://www.youtube.com/watch?v=9yRLd6gjZWU&ab_channel=RaTeX

For Mac OS user, following is the solution that solved my issue:

Change permission on every single Adobe folder to everyone read write:

Documents

Applications

Library Caches

Library Preferences

Library Application Support

Delete Preferences on Startup (cmd – option – shift).

Here we go!

This was it!!!

I can't believe how many things  i tried that were all wrong and much more involved. Then this super simple thing was it.

Thank you PAK1111!

I have tried all of these solutions and still am unable to run AE.

Has anyone figured out how to fix it for the mac version? I'm struggling with this too. I've tried reinstalling and restarting but none of that works.

Hey PAK, i'm having the same problem. Did you ever resolve the issue?