Internal Server Error when starting Backup

Hi,

I always get a internal server error when starting a backup with BackWPup 3.1.4 (free version).
I already tried reinstalling the plugin and I deactivated all other plugins, but it doesn’t work.

I hope someone has an idea what the problem is.

Here is the stuff from BackWPup info tab:

WordPress version 4.2.3
BackWPup version 3.1.4 Get pro.
PHP version 5.4.41-0+deb7u1
MySQL version 5.5.43-0+deb7u1
cURL version 7.26.0
cURL SSL version OpenSSL/1.0.1e
WP-Cron url: https://example.com/wp-cron.php
Server self connect: The HTTP response test get an error “SSL certificate problem: self signed certificate”
Temp folder: /var/www/vhosts/example.com/httpdocs/wp-content/uploads/backwpup-xxx-temp/
Log folder: /var/www/vhosts/example.com/httpdocs/wp-content/uploads/backwpup-xxx-logs/
Server Apache
Operating System Linux
PHP SAPI cgi-fcgi
Current PHP user example
Safe Mode Off
Maximum execution time 60 seconds
Alternative WP Cron Off
Disabled WP Cron Off
CHMOD Dir 0755
Server Time 16:21
Blog Time 18:21
Blog Timezone Europe/Berlin
Blog Time offset 2 hours
Blog language en-US
MySQL Client encoding utf8
Blog charset UTF-8
PHP Memory limit 256M
WP memory limit 40M
WP maximum memory limit 256M
Memory in use 25.25 MB
Disabled PHP Functions: pcntl_alarm, pcntl_fork, pcntl_waitpid, pcntl_wait, pcntl_wifexited, pcntl_wifstopped, pcntl_wifsignaled, pcntl_wexitstatus, pcntl_wtermsig, pcntl_wstopsig, pcntl_signal, pcntl_signal_dispatch, pcntl_get_last_error, pcntl_strerror, pcntl_sigprocmask, pcntl_sigwaitinfo, pcntl_sigtimedwait, pcntl_exec, pcntl_getpriority, pcntl_setpriority,
Loaded PHP Extensions: Core, PDO, Phar, Reflection, SPL, SimpleXML, bcmath, bz2, calendar, cgi-fcgi, ctype, curl, date, dba, dom, ereg, exif, fileinfo, filter, ftp, gd, gettext, hash, iconv, imap, ionCube Loader, json, libxml, mbstring, mcrypt, mhash, mysql, mysqli, openssl, pcntl, pcre, pdo_mysql, pdo_pgsql, pdo_sqlite, pgsql, posix, session, shmop, soap, sockets, sqlite3, standard, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xml, xmlreader, xmlrpc, xmlwriter, xsl, zip, zlib

https://wordpress.org/plugins/backwpup/