Fast Core

[Duck]

Operating System

1. macOS 26 Tahoe

What is this? Why does it come up when I go edit in?

 

[clee01l]

What version of PS do you have installed? Current is v27.8.0

The "FastCore Routines" module is a legacy Photoshop plugin that handled specific processing tasks on older computer architectures. If you receive an error about it not loading, it means you are running a modern Photoshop version on an operating system where this older module is no longer supported

 

[Duck]

Clee, what does it mean and what do I do about it?

 

[clee01l]

Clee, what does it mean and what do I do about it?

If you have the latest version of MacOS (v26.5.1) theLatests version of Lightroom Classic (v15.4.1) and the latest version ofPS (v17.8.0) You Should not see this. What versions of MacOS, Lightroom Classic and Photoshop are installed? Also do you have an Intelor Silicon Mac?

 

[Duck]

I have 27.8.0 PS, Tahoe 26.5.1 and LR 15.4.1. Silicon, too Mac Studio.

 

[clee01l]

I have 27.8.0 PS, Tahoe 26.5.1 and LR 15.4.1. Silicon, too Mac Studio.

I have the same versions. And I have never seen this message. I did some basic research to even understand where the message was coming from Does it happen every time or just that once. If it happens again click on the "About Photoshop". to verify that you did no t open an old version by mistake

 

[Duck]

I am in 27.8

 

[clee01l]

I am in 27.8

I have no explanation as to why you are getting the message.

 

[Jimmsp]

Here is something from Gemini Pro. (in my prompt I said (its ok not to know - no guesses )
BTW, I am a pc user.

The issue is caused by legacy Intel-era plugin files lingering on the user's Apple Silicon Mac Studio. Modern native versions of Photoshop (like 27.8.0) cannot load these older architectural modules.

Here is exactly what is happening and how to resolve it:

The Cause​

The user almost certainly used Apple's Migration Assistant (or a Time Machine restore) when moving from an older Intel Mac to their current Mac Studio. This process blindly copies over hidden legacy Application Support files, preferences, and ancient plugins. When Lightroom uses the "Edit In" command, it launches Photoshop, which scans these folders on startup. Upon hitting the old FastCore module, it throws an architecture mismatch error.

The Fix​

The user needs to clear out the legacy cruft. They should try these steps in order:

• Disable Additional Plugins: Open Photoshop, go to Preferences > Plug-ins, and uncheck Additional Plug-ins Folder if it is enabled. Restart Photoshop.
• Manual Cleanup: Check the global and user-level Adobe plugin folders and delete any old third-party or legacy files. The paths are:
  
  • /Library/Application Support/Adobe/Plug-Ins/
  • ~/Library/Application Support/Adobe/Plug-Ins/
• Clean Reinstall: If the error persists, standard uninstallation won't catch hidden migrated files. The user must use the Adobe Creative Cloud Cleaner Tool to wipe Photoshop and its background application support folders completely, then reinstall a fresh copy of version 27.8.0.

 

[Duck]

Thanks for all the help.