'Illegal Command Sequence' followed by 'Layer does not have a source'

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Community Beginner ,

For a while now, After Effects has been loading up to 99%, and then crashing whenever I open a project. Normally, I just keep trying and eventually it works. This issue persists across every single project.

However, today, this one project refuses to open and hits me with a new error 'Illegal Command Sequence', which takes loads of tries to close the pop-up window, and then it's followed by multiple 'Layer does not have a source' error messages.

I can open the project on another computer, which is strange. I opened it up and Reduced the project (from 75MB to 25MB in size), but this hasn't helped.

Does anyone have a solution for either of these errors? I have tried:

• Removing plug-ins (from ScriptUI Panels folder)

• Starting in Safe Mode

• Reduced the project

• Cleared all Cache

• Importing the project into a new, empty AE project

• Opening from 'File > Open...'

Computer specs:

• Mac Studio M1 Max

• 64GB RAM

• MacOS: macOS Sequoia 15.0.1

• Assets are stored on an external SSD Hard Drive