Failed to make backup of web files, because of unknown backup format gzip (ISPConfig dev version)
short description
After updating the ISPConfig installation on a mutiserver setup the manual and automatic backups do not work anymore.
environment
Operating System: Debian 10.0 (Buster)
Version: ispconfig3-stable-3.1-e69a5b3f683d75e782613577f89e5be3e97d4f27
nginx version: nginx/1.14.2
gzip 1.9
# which gzip
/usr/bin/gzip
PHP 7.3.18-1+0~20200514.58+debian10~1.gbp12fa4f
log entries
28.05.2020-22:27 - DEBUG - Triggered backup routine for domain id 8, action name backup_web_files
28.05.2020-22:27 - DEBUG - safe_exec cmd: mount 2>/dev/null | grep ' on /backup type ' - return code: 0
28.05.2020-22:27 - ERROR - Failed to make backup of web files, because of unknown backup format gzip for website domain.de
28.05.2020-22:27 - DEBUG - Remove Lock: /usr/local/ispconfig/server/temp/.ispconfig_lock