Can you include a screenshot of the error you're getting?
From Site administration ▸ Plugins ▸ Plugins overview what version of Boost is listed? It should be something like 2020061500.
Do you know what version of Adaptable you're trying to upgrade to?
There is a specific forum for Themes so you may wish to post your question there. The Adaptable author is active there and often responds to issues and questions.