Two points noticed when installing 2.4 as an upgrade:

1) The code provided to be altered in the database via SQL did not work as noted. Our programmer altered it from what was recommended at <http://www.minyaa.com/documentation/latest/Installation/Upgrades/ToMinyaa.2.4.html> to the following to get it to function:

DELETE FROM jiraschema.propertystring where id in (SELECT id FROM jiraschema.propertyentry p where property_key like 'jira.plugin.state-.jira.plugin.minyaa%');
DELETE FROM jiraschema.propertyentry where property_key like 'jira.plugin.state-.jira.plugin.minyaa%';

2) The install documentation notes that jira-plugin-minyaa-boot-gadgets-X.Y.Z-2.4.jar needs to be copied to the atlassian-jira-home/plugins/installed-plugins folder. This file is not present in the zip file I downloaded from your site. I'm not sure if this is critical or not.