cannot run illustrator on Mac OS high Sierra

If you cannot (or don't want to) update your system, you can install an older version of Illustrator:

https://helpx.adobe.com/download-install/using/install-previous-version.html

You always need to check software guidelines as to OS requirements. The update and your OS are not compatible. You will need to see if your computer can be updated to a current OS or if you can go back to the previous version of Adobe CC that you were working with.

sounds wierd that everything was working fine and one update after nothing is working

Might look like a simple update but a lot has happened because of that update. Basically, you need to take action to upgrade your operating system.

my Mac is up to date

Your Mac might be up-to-date as far as High Sierra (released 2017) goes but it's running an old, unsupported operating system which is four major versions behind the current Monterey operating system (released 2021).

Current Adobe software only supports the last 3 Apple operating systems: Catalina, Big Sur and Monterey.

The easiest option, if your hardware can handle it, would be to update your operating system from High Sierra to Monterey or Big Sur or Catalina.

https://support.apple.com/en-au/HT212735

What are your hardware specs? Follow these steps to find out.

Minimum system requirements to run Illustrator are listed here:

https://helpx.adobe.com/illustrator/system-requirements.html

The latest version is not compatible with your system.