A recent update of gallery2 removed 3 modules, which, if these had not been
 deactivated within gallery2 beforehand, caused errors in upgraded gallery2
installations.

To remove the remnants of the recently removed uploadapplet, 
slideshowapplet and remote modules, do the following:

In your gallery2 database:
delete from g2_PluginMap where g_pluginId = 'uploadapplet';
delete from g2_PluginPackageMap where g_pluginId = 'uploadapplet';
delete from g2_PluginParameterMap where g_pluginId = 'uploadapplet';
delete from g2_PluginMap where g_pluginId = 'slideshowapplet';
delete from g2_PluginPackageMap where g_pluginId = 'slideshowapplet';
delete from g2_PluginParameterMap where g_pluginId = 'slideshowapplet';
delete from g2_PluginMap where g_pluginId = 'remote';
delete from g2_PluginPackageMap where g_pluginId = 'remote';
delete from g2_PluginParameterMap where g_pluginId = 'remote';

Then, on the host with gallery2 installed, in your g2data directory:
rm -f g2data/cache/module/_all/0/0/*
rm -rf g2data/cache/module/uploadapplet
rm -rf g2data/cache/module/slideshowapplet
rm -rf g2data/cache/module/remote

This will restore any functionality not directly affected by the .jar 
removals, such as adding new items.