Owncloud file delete problem since v. 2.7.x

[ceaseDD]

Steps to reproduce
open the owncloud.cfg file
insert Flag promptDeleteAllFiles=false
when trying to delete all files in ownCloud and then clicking merge changes it crashes.
Expected behaviour
Tell us what should happen

ownCloud should delete all files without the warning message of “Remove All Files”? with the choices of Remove all files or to keep files when the files are deleted from the server, it used to work on v 2.6.x
but now it doesnt

Actual behaviour
Tell us what happens instead

now it just crashes with promptDeleteAllFiles=false

Server configuration
Operating system:
Ubuntu 16.04.7

Web server:
Apache2

Database:
mysql
PHP version:
7.2
ownCloud version: (see ownCloud admin page)
10.5
Updated from an older ownCloud or fresh install:
fresh
Where did you install ownCloud from:
from the official website
Signing status (ownCloud 9.0 and above):
Template for output < 10 lines

1. Client logfile: Output of owncloud --logwindow or owncloud --logfile log.txt
   (On Windows using cmd.exe, you might need to first cd into the ownCloud directory)
   (See also https://doc.owncloud.org/desktop/troubleshooting.html#log-files )

2. Web server error log:

3. Server logfile: ownCloud log (data/owncloud.log):

[TheOneRing]

Thx for reporting will be fixed in 2.7.8 or 2.8