1. Download full package and upgrade package from sourceforge i.e http://e107.org/get-started
2. Upgrade is allowed for all 1.x to 2.1. Check the files and folders that needs to be deleted in next version. This can be checked while logging into admin after upgrade.
3. kindly check and add upgrade method when there is update in 2.x branch. (Current upgrade method support only 1.x to 2.x)
4. PHP REQUIREMENT LINK : http://e107.org/get-started
5. Since e107 2.3.0 version list of files to be deleted can be checked from /e107_system/{{RAND_FOLDER_NAME}}/logs/fileinspector/deprecatedFiles.log. Since post upgrade the script does not ask to delete any folders, we have commented the code to delete folders in upgrade.php. Check this in every version.