Follow this steps to update JoomMap from J3 to J4 correctly.
- Make sure to update your joomla website to version 3.10
- Makue sure your JoomMap version is the last one (v1.3.2) in joomla 3 series
- Update Joomla 3 to Joomla 4 , read this article: https://docs.joomla.org/Joomla_3.x_to_4.x_Step_by_Step_Migration
- Once website update to Joomla 4 , go to joomboost downloads and download JoomMap v4+ then install on your updated website.