With the new year, a new resolution to upgrade some sites to the new CiviCRM 2.1. CiviCRM 2.1 is particularly special because it requires Drupal 6 and it's the first version that supports Drupal 6. So upgrades of existing Drupal 5 sites are difficult, particularly if any custom modules or themes involved. As it turned out, my procrastination was justified. I asked my friend Rob Ellis to help with Maquila Solidarity Network , who I've been working with for a few months , and who decided that the new features in 2.1 were too good to postpone any longer. Rob did the upgrade and discovered two issues on my CentOS 4 server: The CiviCRM installer insists on PHP 5.2.x CiviCRM requires a version of PCRE with unicode None of this sounds very interesting, and I wouldn't post about it, except that I would have thought it wouldn't be as hard to fix as it was. So here's what I did, in case there's someone else out there with CentOS4 (or RHEL4) trying to run CiviCRM 2.1...