MySQL Collations - In the upgrade from older version to G2.1 or newer, step 3 (core module upgrade) might fail for some users with a error similar to
Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE)
What you can do to fix the problem is to edit modules/core/classes/GalleryStorage/MySqlStorage.class and change
function _setConnectionSettings(&$db) { /* MySQL 4.1.0+ support UTF-8, for details, see: http://drupal.org/node/40515 */
to
function _setConnectionSettings(&$db) { return null; /* MySQL 4.1.0+ support UTF-8, for details, see: http://drupal.org/node/40515 */
and edit modules/core/CoreModuleExtras.inc by replacing
case '1.0.27':
with
$storage->execute('SET NAMES "utf8"'); case '1.0.27':
Then start the upgrade wizard again. You should now be able to successfully run all upgrade steps. After the upgrade, change MySqlStorage back. CoreModuleExtras.inc does't matter, but you can revert that change too after the upgrade.
Note: Earlier MySQL had a related bug. Upgrade to MySQL 4.1.16 (or higher) or 5.0.17 (or higher) to resolve this problem: http://bugs.mysql.com/bug.php?id=10446