I have an issue which I have searched for an not found. but have a temporary fix for. I have put spaces around all my possible paths to allow me to submit. Running ISPConfig 3.1.13 Patch 1 on Debian "Debian GNU/Linux 9 (stretch)" (Fully patched) the roundcube webmail client will not attachments properly. They attach but they do not send. which is caused by round cube not being able to use the roundcube home temp dir. Error from Log I have tried to fix open_basedir (Made no difference) I went back through the installation instructions (Which did not precisely match the server) but that made no difference. I have changed my temp_dir to be / tmp defaults.inc.php:$config['temp_dir'] = '/ tmp'; this fixes it, but is a poor fix Looking for Ideas and maybe help someone else who has this problem.
I removed the log entry as it would not allow me to post even though there where no links. (I still have spaces around all my paths)
Check which temp dir is used by default and ensure that it is writable by the web server used, normally www-data. Using /tmp is fine as well.