My conclusion is that the cause of this problem is in the 'sql_mode'. That setting is managed by the hosting partner, so I had to make a workaround.
In the logging of Coppermine I found errors:
Quote
GROUP BY r.aid
ORDER BY NULL' in index.php on line 362 the following error was encountered:
1055 : 'databasename.c.cid' isn't in GROUP BY
I edited index.php from this:
Quote
// album stats for regular albumsTo this:
$sql = "SELECT r.aid, c.cid, COUNT(pid) AS pic_count, MAX(pid) AS last_pid, MAX(ctime) AS last_upload, depth AS level, lft
FROM {$CONFIG['TABLE_CATEGORIES']} AS c
INNER JOIN {$CONFIG['TABLE_ALBUMS']} AS r ON r.category = c.cid
INNER JOIN {$CONFIG['TABLE_PICTURES']} AS p ON p.aid = r.aid
WHERE c.depth >= $CURRENT_CAT_DEPTH + 1
AND approved = 'YES'
$forbidden_set
$lft_rgt
GROUP BY r.aid
ORDER BY NULL";
Quote
// album stats for regular albums
$sql = "SELECT r.aid, c.cid, COUNT(pid) AS pic_count, MAX(pid) AS last_pid, MAX(ctime) AS last_upload, depth AS level, lft
FROM {$CONFIG['TABLE_CATEGORIES']} AS c
INNER JOIN {$CONFIG['TABLE_ALBUMS']} AS r ON r.category = c.cid
INNER JOIN {$CONFIG['TABLE_PICTURES']} AS p ON p.aid = r.aid
WHERE c.depth >= $CURRENT_CAT_DEPTH + 1
AND approved = 'YES'
$forbidden_set
$lft_rgt
GROUP BY r.aid, c.cid, c.depth, c.lft
ORDER BY NULL";
Then the error dissapeared and Coppermine worked like a charm!