iMac can't connect to App Store

We need to see what all is running, a report from this will not display any personal info...

Using EtreCheck - Apple Community

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Thanks for Old Toad’s etrecheck instructions…

Slow iMac 2017 - Apple Community

Use the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

If you have installed any third-party AV, Protecting, Cleaning ware or use a VPN, you need to uninstall those according to the developers instructions.

Then startup in Safe Mode followed by a normal restart and see if you can access the App Store.

see > Use safe mode on your Mac - Apple Support

melonid1 wrote:

Ok, well, thanks again, I've removed CCleaner.app from my Mac, emptied the trash, restarted the PC.

I now try to logon to the App Store and continue to get the same error message "Cannot Connect, Something went wrong. Please try again. Retry button (which does nothing)"

Any other thoughts? Much appreciate your replies!

You're welcome.

Startup in Safe Mode followed by a normal restart, then try and access the App Store.

see > Use safe mode on your Mac - Apple Support

If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support

You're welcome.

Your Mac does not benefit or need any type of third-party junk-ware.

see > macOS - Security - Apple

In fact, most will do more harm than good.

You're welcome.

Did you try the last step?

If you tried all of the above steps and you still can’t connect, contact Apple Support.

Right click on the App & choose Open...