Question about Upgrading from OJS 3.0 to 3.3

We have and OJS 3.0 site running on a RHEL 7 server under PHP 5.4 PHP-FPM, using the Nginx web server. Version 7.4 of PHP is also installed on that server. (I tested running OJS 3.0 with PHP 7.4, but the site did not come up.) We need to upgraded OJS, since the Crossref DOI plugin no longer works in version 3.0 (this information came from Crossref support).

Two questions:

  • Is OJS version 3.3 compatible with PHP version 7.4?

  • Other than setting the Nginx configuration file for the site to use the PHP-FDM version 7.4 after the upgrade, are there any other issues not documented at that I should be aware of before attempting the upgrade?

    A third question - is it possible to upgrade the Crossref DOI plugin without doing a full upgrade to OJS? I have not been able to find a place to download version 3.2 of the plug in; all I find are pages documenting how to configure it.

         Thanks, Kerry