Ignite Gallery version 5.2 and below do not work in Joomla 6.
Version 5.3 of Ignite Gallery was released on the 20th of October 2025. Version 5.3 of Ignite Gallery works in Joomla 6, and in Joomla 5 (and Joomla 4)
To upgrade from Joomla 5 to Joomla 6, please update Ignite Gallery to version 5.3, no extra steps are required.