Google Analytics Error 20006 is caused by a conflict in domain names between your GA property and your DNS settings. Luckily, the problem is easy to fix!
Error 20006 fix
1. Go to the admin tab, select your property, then select property settings and change the default URL. You will either have to remove or add “www.”.
Admin -> Property -> Property Settings
2. Back to the admin tab, select your property (which is probably selected by now). Now select view settings in the view (profile) column of your admin page. In this case we will have to change the website URL, again either remove or add “www.”.
Admin -> View (Profile) -> View Settings
3. Clear your browser cookies and relog into Google Analytics.
Just let me know in the comments if you have any problems fixing the error and we’ll fix it together!