I got this error, don´t know why, it did work earlier today.
Error (ERROR_BAD_PARAMETER)
in modules/core/classes/helpers/GalleryEntityHelper_simple.class at line 39 (GalleryCoreApi::error)
in modules/core/classes/GalleryCoreApi.class at line 2361 (GalleryEntityHelper_simple::loadEntitiesById)
in init.inc at line 208 (GalleryCoreApi::loadEntitiesById)
in main.php at line 197
in main.php at line 104
in main.php at line 88
Debug Output
file_exists(/var/g2data/cache/module/_all/0/0/GalleryFactoryHelper_loadRegistry.inc)
file_exists(/var/www/gallery2/modules/rewrite/classes/parsers/pathinfo/PathInfoUrlGenerator.class)
getParameter shortUrls for rewrite plugin
file_exists(/var/g2data/cache/module/rewrite/0/0/0.inc)
getParameter pathinfo.parser for rewrite plugin
getParameter session.lifetime for core plugin
file_exists(/var/g2data/cache/module/core/0/0/0.inc)
getParameter session.inactivityTimeout for core plugin
(mysqli): SET NAMES "utf8"
(mysqli): SELECT g2_Schema.g_info FROM g2_PluginMap, g2_Schema
WHERE g2_PluginMap.g_pluginId = g2_Schema.g_pluginId
AND g2_Schema.g_type = 'map' AND g2_PluginMap.g_active = 1
(mysqli): SELECT g_userId, g_remoteIdentifier, g_creationTimestamp,
g_modificationTimestamp, g_data FROM g2_SessionMap WHERE
g_id='5a693644f2cb5ccb1acc5f37809add85'
(mysqli): BEGIN
(mysqli): DELETE FROM g2_SessionMap WHERE
g_id='5a693644f2cb5ccb1acc5f37809add85'
getParameter cookie.domain for core plugin
getParameter cookie.path for core plugin
getParameter session.lifetime for core plugin
getParameter language.useBrowserPref for core plugin
getParameter default.language for core plugin
controller , view
Loading plugin core
Class not defined, trying to include it.
file_exists(/var/www/gallery2/modules/core/module.inc)
core plugin successfully instantiated
file_exists(/var/g2data/versions.dat)
file(/var/g2data/versions.dat, )
getParameter id.anonymousUser for core plugin
[1311271404] can't guarantee 5 -- extending!
file_exists(/var/g2data/cache/module/_all/0/0/GalleryPluginHelper_fetchPluginStatus.inc)
getParameter default.theme for core plugin
Loading plugin
Class not defined, trying to include it.
file_exists(/var/www/gallery2/themes//theme.inc)
file_exists(/var/g2data/cache/theme/_all/0/0/GalleryPluginHelper_fetchPluginStatus.inc)
Loading plugin
Class not defined, trying to include it.
file_exists(/var/www/gallery2/themes//theme.inc)
getParameter id.adminGroup for core plugin
(mysqli): SELECT g_userId FROM g2_UserGroupMap WHERE g_userId=0 AND
g_groupId=0 LIMIT 1
realpath(/var/www/gallery2/modules/core/classes/../../../)
realpath(/var/www/gallery2/)
Site URL: http://www.fjollrosa.se/gallery2/main.php
Thanks! 
I hope...
Posted: Thu, 2011-07-21 18:16
Posts: 8339
Clear gallery's caches http://www.fjollrosa.se/gallery2/lib/support
and your browser's cache
if not resolved put gallery into debug mode and copy/past the debug to a txt file and attach it to this forum
FAQ: How to set/use Gallery in debug mode?
-s
FlashYourWeb and Your Gallery with The E2 XML Media Player for Gallery2
Posts: 15
That was fast! Many thanks!
It worked perfectly!