How to troubleshoot startup issues in After Effects using the Startup Repair Options.
The Startup Repair Options are an addition to After Effects version 23.4 and later.
What does Safe Mode do?
- Safe mode will launch After Effects with default Preferences. This allows you to isolate problems with corrupt Preferences. Your custom Preferences will be retained after exiting Safe Mode.
- Disable third-party plugins during launch to determine if a plugin is causing startup issues.
How to get started?
1. Press Ctrl + Alt + Shift (Command + Shift + Option on Mac) and launch After Effects to show the "Startup Repair Options" dialog box. Select the "Start in Safe Mode" option.

2. After selecting the "Start in Safe Mode" option, you’ll see a "Starting in Safe Mode" dialog box. Keep the "Disable 3rd party plugins during session" unchecked and click OK. This will launch After Effects with default preferences with the plugins activated.

3. If After Effects successfully launches in Safe Mode, there is likely something corrupt or problematic in your existing preferences.
Reset your preferences by relaunching After Effects and selecting the "Reset Preferences" option in the "Startup Options dialog box."
Note: To backup your Preferences, navigate to the following file path and copy the 23.4 folders to another location.
Windows: C:\Users\username\AppData\Roaming\Adobe\After Effects\23.4
macOS: ~/Library/Preferences/Adobe/After Effects/23.4

4. If you do not load past the splash screen, it might be a plugin-related issue. To isolate any plugin-related issues, relaunch After Effects in Safe Mode (repeat step 1) and select the "Disable 3rd party plugins during session" checkbox. (Note: If you do not see the "Startup Repair Options" dialog box, restart After Effects in Safe Mode again.)

5. Once After Effects successfully loads past the splash screen, go to Effect > Manage Effects, enable an effect, and restart After Effects till you can isolate the problematic effect. After isolating the problematic effect, please reach out to the plugin manufacturer and create a post on the After Effects community to help users experiencing similar issues.

If you're still experiencing startup issues after following these steps, please create a new post in the After Effects Community.
Here's a video tutorial on the start-up repair menu:

