No longer provideing premodded files, because they cause more trouble then they are worth. At this time the the upgrade instructions would be longer then the install instructions. If you only have AGCM installed with some minor mods, then it is best to backup your current files and database, download the latest version on my site and run the uninstaller found in the install folder of the package. Then remove all the files on your site, minus the attachment folder if you use the attachment mod,and the images folder and config.php. Then reupload a new copy of phpBB 2.0.21 and reinstall the latest version of AGCM. Thier were significant changes to the code as well as the variable used by AGCM was changed from $colors to $color so its part of the reason why its best to start with fresh files.