Updating for anyone having problems.
VPN error happens when your windows doesn't recognise the network of your hamachi. Or sometimes it can fail to load up right or even not even show in your network adaptor page.
If you go to device manager & you will see the hamachi network in the list, but with a yellow triangle on it. All you should need to do is right click it, disable it & then enable it. This should put the network adaptor back in your network adaptor page & will be working as is.
If you do need to uninstall & reinstall. I would like to suggest you uninstall the network adaptor from device manager first, and select delete drivers if option is available. Then uninstall hamachi with all user settings. If you don't do it this way, Hamachi will leave behind settings & when you reinstall it, it will just reproduce the same error again & again.
I've tested this when experiancing it on one of my childrens computers & it fixed it & remained fixed since.
Another issue that might be you're problem. Hamachi netowkr is set as Public. If you can't manually set this to private. You may need to open up regedit. Just type regedit in your search box if your on windows 10 or run regedit if on earlier versions. Navigate to the following address.
Now, you should see in the Profiles folder, other folders that are just a random mix of letters & numbers. If you click once on each one, on your right, you will see the details of each folder. You may see you're wifi settings that will be listed as ProfileName. Well, find the one's that just say Network. At the top, look for catagory. If the Data value is (0). Right click it, and click modify. Change the number from 0 to 1 & then click OK. This has now change the network from public to Private. And seeing as you know who is on your Hamachi network, there's no reason for it to be publick, which severely restricts & limits it's ability to a point of blocking it.
If you get stuck, just watch this video tutorial on how to do it.
Hope this helps!