Often when there is a new release of Mautic, those of us using Mautic Whitelabeller have the frustration that it is not compatible with the current version.
Here are the steps to correct this:
Unzip the file, then go and edit the file compare.php
compareMauticVersions($v1_path, $v2_path, $v3_path);
'; print_r($compare); echo '
Simply add in your version for path 4 and update.
Then go to templates directory and copy the lates directory to the new version
cp -R 3.1.0/ 3.2.1
Then remember to chown -R the new directory