SOLVED: com.apple.commerce.client error 500

Just figured out how to solve this and thought I'd share. It is related to allowing incoming connections. You can follow this link to fix it https://support.apple.com/en-us/HT201400

Otherwise here are the solutions

• Click your desktop to make sure that you're in Finder.
• From the menu at the top of your computer screen, choose Go > Go to Folder.
• In the box, enter /var/db/crls/.
• Click Go.
• Drag the files labeled crlcache.db and ocspcache.db to the Trash.
• If prompted, enter your administrator password.
• Restart your computer, then try to connect to the iTunes Store, App Store, or Book Store.

The issue occurs when a user tries to download or sign into the Mac App Store and the solution is to delete the crlcache.db & ocspache.db, restart then sign in to the Mac App Store. Best of luck