proftpd dies after restart (logrotate)

[ft]

# service proftpt status
ProFTPD is started in standalone mode, currently running.

# service proftpd restart
* Stopping ftp server proftpd [ OK ]
* Starting ftp server proftpd [ OK ]

# service proftpt status
ProFTPD is started in standalone mode, currently not running.

In "/etc/logrotate.d/proftpd-basic" -> "invoke-rc.d proftpd restart" -> same result

In "/var/log/proftpd/proftpd.log" I only see this:
2014-03-17 09:14:46,869 myserver proftpd[17312] 192.168.5.32: ProFTPD killed (signal 15)
2014-03-17 09:14:46,870 myserver proftpd[17312] 192.168.5.32: ProFTPD 1.3.5rc3 standalone mode SHUTDOWN

I have tried to add "DebugLevel 10" and "SystemLogLevel debug" to "/etc/proftpd/proftpd.conf" but I don't got further informations.

For me this happens with and without tls enabled. My private key has no passphrase, so a simpe "restart" should work.

On Debian side I found this (maybe it helps):
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=675081

Workarround:
Add in "/etc/init.d/proftpd" a "sleep 2" to line 180 "(force-reload|restart" part).

After Workarround:
# service proftpd status
ProFTPD is started in standalone mode, currently running.

# service proftpd restart
 * Stopping ftp server proftpd [ OK ]
 * Starting ftp server proftpd 2014-03-17 09:29:13,979 bu-wbs-apache01 proftpd[18496] 10.15.32.74: 10.15.32.74:21 masquerading as 83.65.149.234
                                                                                                                                                                                                                               [ OK ]

# service proftpd status
ProFTPD is started in standalone mode, currently running.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: proftpd-basic 1.3.5~rc3-2.1ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-17.37-generic 3.13.6
Uname: Linux 3.13.0-17-generic x86_64
ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
Date: Mon Mar 17 09:11:34 2014
InstallationDate: Installed on 2014-02-11 (33 days ago)
InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140211)
SourcePackage: proftpd-dfsg
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ruben (info-rubenfelix)]

You can also remove the logrotate config file. That keep proftp running but your logfile might be big.