Dear @Vitaliy,
I tested the docxConverter with the last OJS version 3.2.1-1, even if it is made for versions 3.1+ and get a Internal Server Error when I try to convert a .docx file. I tested in two different servers with the same error.

Have you tested yet the plugin or do you plan to upgrade to be compatible with the last version of OJS?
Regards,
José Carvalho
Hi @josekarvalho,
It should work with 3.2+, are there any errors in PHP logs?
Hi @Vitaliy,
I manage to solve this!
The logs with warnings and a fatal error:
[01-Jul-2020 03:45:21 America/Los_Angeles] PHP Warning: Declaration of DocxToJatsPlugin::register($category, $path) should be compatible with LazyLoadPlugin::register($category, $path, $mainContextId = NULL) in /home/jk_karona/ojs3.josekarvalho.net/plugins/generic/docxConverter/DocxToJatsPlugin.inc.php on line 0
[01-Jul-2020 03:45:21 America/Los_Angeles] PHP Warning: require_once(/home/jk_karona/ojs3.josekarvalho.net/plugins/generic/docxConverter/classes/…/docxToJats/vendor/autoload.php): failed to open stream: No such file or directory in /home/jk_karona/ojs3.josekarvalho.net/plugins/generic/docxConverter/classes/DOCXConverterDocument.inc.php on line 13
[01-Jul-2020 03:45:21 America/Los_Angeles] PHP Fatal error: require_once(): Failed opening required ‘/home/jk_karona/ojs3.josekarvalho.net/plugins/generic/docxConverter/classes/…/docxToJats/vendor/autoload.php’ (include_path=’.:’) in /home/jk_karona/ojs3.josekarvalho.net/plugins/generic/docxConverter/classes/DOCXConverterDocument.inc.php on line 13
I checked the line of the error and it ask for a file in the “docxToJats” folder inside the plugin files. This folder was empty. So I went to GitHub - Vitaliy-1/docxConverter: Plugin for OJS 3 that parses DOCX and converts it to JATS XML format, clicked on the folder of “docxToJats” (GitHub - Vitaliy-1/docxToJats at bd66ac39f471a5ff9b16f0a21993eaf5ba36869d), and copy this content to the plugin on the server.
Now it works. This issue is a consequence of using FTP to include the plugin. Is there any plans to include this plugin on the OJS Plugin Gallery?
Thanks,
José Carvalho
Glad that you’ve resolved it 
Yes, I plan to add it to the gallery in late autumn.
Nice! It will be easy for the community to test and use.