I have no idea.
Since my last message, other duplicated albums have been created (with a slash before their names).
Maybe something about the cache ?
Or maybe if a thumbnail is manually selected by the user ?
For example, in the database I get this :
album01/albumtitle title:a:1:{s:5:"fr_FR";s:19:"Album TITLE ";}
and created at the same time I get this :
/album01/albumtitle title:albumtitle

Anyway I have no errors about that in the debug log but I get that :

`
{64956:Thu, 21 Nov 2013 20:34:46 GMT}

WARNING: Cannot modify header information - headers already sent by (output started at /home/XXX/public_html/zp-core/lib-GD.php:114) in /home/XXX/public_html/zp-core/functions-image.php on line 30

header called from imageError (functions-image.php [30])

from cacheImage (functions-image.php [493])

from i.php [165]

{64956:Thu, 21 Nov 2013 20:34:46 GMT}

WARNING: Cannot modify header information - headers already sent by (output started at /home/XXX/public_html/zp-core/lib-GD.php:114) in /home/XXX/public_html/zp-core/functions-image.php on line 31

header called from imageError (functions-image.php [31])

from cacheImage (functions-image.php [493])

from i.php [165]

{64956:Thu, 21 Nov 2013 20:34:46 GMT}

WARNING: Cannot modify header information - headers already sent by (output started at /home/XXX/public_html/zp-core/lib-GD.php:114) in /home/XXX/public_html/zp-core/functions-image.php on line 32

header called from imageError (functions-image.php [32])

from cacheImage (functions-image.php [493])

from i.php [165]
`
Last : it only happened to albums of a connected uploader since the last database clean up today.

The warnings are downstream issues, but there should have been an error logged by the imageError function mentioned. The error is that a particular image failed in the image create function of the graphics library. The message should tell you the image name as well.

I do not understand "connected uploader", but that is probably the key information since it seems to be the source of the problem.

Also you can install the latest support build [550e100083] as I have added some more debugging of this problem which might help.

Hi stephen,
by "connected uploader" I mean regularly registered users who have the right to edit their own album and to upload pictures.
It seems that this happens only after these users edit or upload some pictures.

I'll give a try to this release and let you know.

Thank you.