Missing user details after upgrade to 2.0.4
As a result of a fault in the upgrade logic in 2.0.4 you may find that after the upgrade from a 2.0.x version your user details will be missing. If you then view Contacts you will find a number of contacts with no details, but you will still have contacts with the correct details.
In most cases you will be able to easily identify which users are related to which contact and using User Admin you should be able to link users to the correct contacts. If you have a large number of users/contacts it may be possible to use SQL direct into the database to update the details. The correct SQL to use will depend entirely on your use of contacts and users and will require you to correctly analyse that data.
If you haven't yet upgraded to 2.0.4 from a prior 2.0.x release, please delete the db/upgrade_to_204.php file before running the install/upgrade utility. If you have upgraded, but have not made any data changes, then restore your backup (you did take a backup, didn't you?), and then remove the db/upgrade_to_204.php file and re-run the upgrade utility.
A release is being prepared to resolve this issue, however it will not be able to automatically fix linkages broken by the 2.0.4 upgrade.