Something

A fatal error has occurred
Required "charset" not specified in preferences SQL configuration. The file /usr/share/horde3/lib/../config/conf.php should contain a $conf['prefs']['params']['charset'] setting.
[line 525 of /usr/share/horde3/lib/Horde.php]

Details (also in Horde's logfile):

object(PEAR_Error)#9 (8) {
  ["error_message_prefix"]=>
  string(0) ""
  ["mode"]=>
  int(1)
  ["level"]=>
  int(1024)
  ["code"]=>
  NULL
  ["message"]=>
  string(179) "Required "charset" not specified in preferences SQL configuration.

The file /usr/share/horde3/lib/../config/conf.php should contain a $conf['prefs']['params']['charset'] setting."
  ["userinfo"]=>
  NULL
  ["backtrace"]=>
  array(5) {
    [0]=>
    array(7) {
      ["file"]=>
      string(23) "/usr/share/php/PEAR.php"
      ["line"]=>
      int(566)
      ["function"]=>
      string(10) "PEAR_Error"
      ["class"]=>
      string(10) "PEAR_Error"
      ["object"]=>
      object(PEAR_Error)#9 (8) {
        ["error_message_prefix"]=>
        string(0) ""
        ["mode"]=>
        int(1)
        ["level"]=>
        int(1024)
        ["code"]=>
        NULL
        ["message"]=>
        string(179) "Required "charset" not specified in preferences SQL configuration.

The file /usr/share/horde3/lib/../config/conf.php should contain a $conf['prefs']['params']['charset'] setting."
        ["userinfo"]=>
        NULL
        ["backtrace"]=>
        array(5) {
          [0]=>
          array(7) {
            ["file"]=>
            string(23) "/usr/share/php/PEAR.php"
            ["line"]=>
            int(566)
            ["function"]=>
            string(10) "PEAR_Error"
            ["class"]=>
            string(10) "PEAR_Error"
            ["object"]=>
            *RECURSION*
            ["type"]=>
            string(2) "->"
            ["args"]=>
            array(5) {
              [0]=>
              string(179) "Required "charset" not specified in preferences SQL configuration.

The file /usr/share/horde3/lib/../config/conf.php should contain a $conf['prefs']['params']['charset'] setting."
              [1]=>
              NULL
              [2]=>
              int(1)
              [3]=>
              int(1024)
              [4]=>
              NULL
            }
          }
          [1]=>
          array(7) {
            ["file"]=>
            string(31) "/usr/share/horde3/lib/Horde.php"
            ["line"]=>
            int(524)
            ["function"]=>
            string(10) "raiseError"
            ["class"]=>
            string(4) "PEAR"
            ["object"]=>
            object(Prefs_sql)#7 (9) {
              ["_params"]=>
              array(3) {
                ["phptype"]=>
                bool(false)
                ["table"]=>
                string(11) "horde_prefs"
                ["driverconfig"]=>
                string(5) "horde"
              }
              ["_db"]=>
              NULL
              ["_connected"]=>
              bool(false)
              ["_prefs"]=>
              array(37) {
                ["default_identity"]=>
                array(3) {
                  ["v"]=>
                  int(0)
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  int(0)
                }
                ["identities"]=>
                array(3) {
                  ["v"]=>
                  string(6) "a:0:{}"
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(6) "a:0:{}"
                }
                ["id"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(0) ""
                }
                ["fullname"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(0) ""
                }
                ["from_addr"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(0) ""
                }
                ["security_question"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(0) ""
                }
                ["security_answer"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>
                  int(10)
                  ["d"]=>
                  string(0) ""
                }
                ["alternate_email"]=>
                array(3) {
                  ["v"]=>
                  string(0) ""
                  ["m"]=>