If you found an "updated" CS4 serial number online, it likely will not work.
The update was specifically for the serial number, which had been causing some issues for users in the past. Apparently, some users had been experiencing problems with their serial numbers being flagged as invalid, even though they were genuine. Adobe had taken notice of this issue and was releasing a patch to fix it. adobe illustrator cs4 serial number updated
// Concept: Updating Serial Number via ExtendScript var doc = app.activeDocument; var serialNumber = prompt("Enter new serial number", "XXXXXXXXXXXX"); If you found an "updated" CS4 serial number
If you are installing from a Creative Suite DVD, you can choose to install only Illustrator CS4 by selecting Custom Install. Adobe had taken notice of this issue and
Installing and activating Photoshop CS4 Extended - Adobe Community
The smartest path forward is not to resurrect a discontinued product but to embrace the rich ecosystem of modern vector graphics applications available today. From Inkscape to Vectorpea, from Affinity Designer to Canva, today’s designers have access to powerful, secure, and often completely free alternatives that honor the legacy of CS4 while moving confidently into the future.