Supported PHP Versions
Islandora supports Drupal 7's list of supported PHP versions as layed out in their PHP requirements. This means that our testing matrix will include all of these versions of PHP. Given the age and stability of the project, it is unlikely to change any time soon. If, however, the Drupal project jettisons support for older PHP versions, then Islandora will follow suit.
If your PHP version is on the list linked above, you're good to go for the foreseeable future. If not, you will need to upgrade to at least the minimum supported version in order to keep your installation up to date. You may certainly stay on an older version with the understanding that you will be missing out on any future updates.
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