Illustrator 2019 crashing on launch on macOS Catalina

Check "Run Diagnosis" at first.

Remove your custom plugins in "Plug-In" folder.

Here is the details,

https://community.adobe.com/t5/illustrator/illustrator-24-0-1-crashing-on-macos-catalina-10-15-1/m-p/10834552#M160222

Hi there,

We’re so sorry to hear about this. I would request if you can try following these steps and let us know if that helps:

• Share crash logs by following these steps: https://helpx.adobe.com/in/illustrator/kb/crash-next-steps.html 
• Try booting the system into Safe Mode (https://helpx.adobe.com/in/x-productkb/global/start-safe-boot-mode-mac.html) and check how it works there. It starts your system so that it performs certain checks and prevents third party software/ services from automatically loading or opening. If it works fine in Safe mode, then there is some third party service or application like antivirus, plugins or web extensions which is conflicting with the Illustrator.
• If that doesn't help either, login to root account (https://support.apple.com/en-in/HT204012). Check how application works there. If it works fine there, then it could be related to permission errors. Follow these steps to repair permission errors: https://helpx.adobe.com/in/illustrator/kb/preferences-folder-read-only-error.html 
•  If nothing helps, then we need to troubleshoot this on a live session. Please head here (https://helpx.adobe.com/support.html) and select the chat button in the lower-right corner of the page. We can help on a live session that way. 

Regards,

Srishti

At the moment no version is officially compatible with 10.15.
If you are sure to use it, return it to 10.14 or lower.

To rebuild preferences on a Mac:

The User Library folder in which Illustrator’s preferences are stored is hidden by default on most Macintoshes. To access it make sure that Illustrator is closed and click on the desktop to launch a Finder Window (Command-N).With this window in column view follow the path User>Home folder (it’s the folder with an icon that looks like a house—it may have the user’s name rather than “Home”) and click on the Home folder. With the Option Key pressed choose Library from the Finder Go Menu. “Library” will now appear within the Home folder. Within the Library folder find the folder called Preferences and within it find the folder called “Adobe Illustrator <Version #> Settings” (earlier versions of Illustrator might just say “Adobe Illustrator”) and the file called “com.adobe.Illustrator.plist” and delete both that folder and that file. When Illustrator is next launched it will create new preference files and the program will be restored to its defaults.

The advantage of manually deleting preference files in this manner is that after you’ve reset up the program (make sure that no document window is open) to your liking, you can create copies of your personalized “mint” preference files (make sure that you quit the program before copying them—that finalizes your customization) and use them in the future to replace any corrupt versions you may need to delete.

Did you rebuild the preferences after installing the new system?

Do you have a Wacom? Their driver is not yet ready for Catalina and might interfere.

So this is the latest version?

Are any plugins installed?

all fonts checked and OK?