Moodle 3.1 to 4.4 Upgrade

I am in need of an expert with profound skills in Moodle to upgrade my current Moodle from version 3.1 to version 4.4. The project involves dealing with a current installation that has custom themes and plugins.

Key Requirements:

- Experience with upgrading different Moodle versions, preferably to the latest Moodle version 4.4.
- Knowledge in managing and testing custom themes and plugins during the upgrade.
- Familiarity with latest Moodle features would be beneficial to ensure smooth transition.

Kindly note that while upgrading, all functionalities and customizations should be preserved. Since no specific new features or functionalities were requested, the focus should be on a smooth upgrade process, maintaining the integrity of the current system. Also, the total number of users utilizing the platform is unspecified, meaning the solution has to be scalable and robust.

Skills and Experience:

- Proven track record with Moodle upgrades.
- Experience handling Moodle customizations during upgrades.
- Knowledge of Moodle 4.4. features or above.
- Good problem-solving skills and attention to detail.
- Ability to ensure minimal downtime during the upgrade process.