UPDATE: I was able to enable Akonadi playing around with KDE Wallet.
Here is what I did:
Go into System Settings > Account Details > KDE Wallet
Then scroll down and click Launch Wallet Manager, click around and close.
Next go into Plasma Services and enable Akonadi and click apply.
Note: Sometimes I had to click apply two or three times before I heard the harddrive tick and it to actually apply. I'm still not 100% sure what is going on, more testing is needed. But as of right now it is enabled and woking, no more kmail or reminder errors.
Here is what I did:
Go into System Settings > Account Details > KDE Wallet
Then scroll down and click Launch Wallet Manager, click around and close.
Next go into Plasma Services and enable Akonadi and click apply.
Note: Sometimes I had to click apply two or three times before I heard the harddrive tick and it to actually apply. I'm still not 100% sure what is going on, more testing is needed. But as of right now it is enabled and woking, no more kmail or reminder errors.