This is common error occur due to wrong permission setting in Gallery2 data directory.? During module uninstall, gallery2 restore directory permission and other changes as it was before the module installation. This feature sometime break gallery directory permission and directory does not work.? See Image bellow for exact error description.
Try changing gallery data directory “/g2data” permission to 777. If this does not fix your problem then try changing permission to “/g2data/smarty/templates_c“. After this step delete all content including directory inside “/g2data/smarty/templates_c” directory. This should fix ERROR_PLATFORM_FAILURE problem.