Unknown Error 18.020 on launch - Illustrator

Hello ​@Mehmet284054325b9o 

I hope the suggestions shared earlier helped resolve the problem. If not, kindly share more details, like the exact version of the OS/Illustrator installed, so we can investigate further.

Looking forward to hearing from you.
Anubhav

Hello ​@Mehmet284054325b9o 

I’m sorry to hear about your experience. I hope Argeads and Monika’s suggestions helped resolve the problem. If not, kindly try the suggestions shared in this help article (https://helpx.adobe.com/illustrator/kb/fix-crash-plugin.html) and let us know how it goes.
 

Looking forward to hearing from you.
Anubhav

Hello everyone again,

After two days of searching I want to share a solution in case it helps others experiencing the same issue.

I was getting this error on launch:

“An unknown error has occurred (18,020). Adobe Illustrator will now quit.”

The application would crash during startup.

After checking Event Viewer, I found:

• Faulting module: ntdll.dll

• Exception code: 0xc0000374 (heap corruption)

This initially looked like a Windows or system issue.

However, after carefully watching the splash screen, I noticed it was crashing during:

Initializing plug-ins… SKLPRandomOpacity.aip

The problem was caused by the third-party plugin:

SKLPRandomOpacity.aip

Once I removed the plugin from the Illustrator Plug-ins folder, Illustrator 2026 launched normally.

For reference:

• Illustrator Beta worked fine (likely because it didn’t load that plugin).

• Stable version crashed every time.

• Windows was fully updated.

• No system corruption was found.

Solution:

Remove or move this file (or other plugins) from:

C:\Program Files\Adobe\Adobe Illustrator 2026\Plug-ins 

or the equivalent Plug-ins directory.

After removing the plugin, Illustrator launches normally.

Hope this helps someone else.

Same here!

I have already tried the following troubleshooting steps:

• Restarted the computer

• Reset Illustrator preferences

• Signed out and back into Creative Cloud

• Checked for Windows updates

• Checked for GPU updates

• Ran the application as Administrator

The issue still persists.

Creative Cloud opens normally, but Illustrator fails to launch with this error.

On my second PC everything runs smoothly.

Windows 11

Which system is it?

Does it help when you reset the preferences? https://helpx.adobe.com/in/illustrator/using/setting-preferences.html