OK, i think i found the bug…
Before roundcube r731 (think release 0.1-r1) it used ASCII as default character encoding for its session-table. It was changed (bug #1484456) but they only updated the initial SQL, the update.sql does not contain any conversion. As long as you don't disable caching the plugin will save rules inside the session - if there any UTF8-Chars the SQL-query breaks and rc killes the session.
Quick and dirty fix:
Code:
ALTER TABLE `session` ENGINE = InnoDB DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci
ALTER TABLE `session` CHANGE `sess_id` `sess_id` VARCHAR( 40 ) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ,
CHANGE `ip` `ip` VARCHAR( 15 ) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ,
CHANGE `vars` `vars` TEXT CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL
If you have a database that was created with a early rc-version you should recreate all tables - there are more changes that are not inside the update.sql (e.g. MyISAM -> InnoDB)