Help restoring folders from trash bin

Hi,
recently some folders were deleted form my owncloud server and I tried to restore them as descried below. Since I have no backup of these folders I would be grateful for any help I can get to restore them.

Steps to reproduce

Not reproducible

Expected behaviour

Accidentally deleted folder should be restored from the trashbin with the webinterface

Actual behaviour

It was not possible to restore all folders. Received the Message "Couldn't restore folder".

Server configuration

Operating system: Ubuntu 16.04 LTS

Web server: Apache/2.4.18 (Ubuntu)

Database: QSL

PHP version: PHP 7.0.18-0ubuntu0.16.04.1

ownCloud version: ownCloud 9.1.6 (stable)

Updated from an older ownCloud or fresh install: updated

Where did you install ownCloud from: webpackage

The content of config/config.php:

  "system": {
        "updatechecker": false,
        "instanceid": "ockztzlln0e3",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "schiedung.ddnss.de",
            "192.168.0.40"
        ],
        "datadirectory": "\/var\/www\/owncloud\/data",
        "overwrite.cli.url": "https:\/\/schiedung.ddnss.de\/owncloud",
        "dbtype": "sqlite3",
        "version": "9.1.6.2",
        "logtimezone": "UTC",
        "installed": true,
        "maintenance": false,
        "theme": "",
        "loglevel": 0
    }

List of activated apps:

  "system": {
        "updatechecker": false,
        "instanceid": "ockztzlln0e3",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "schiedung.ddnss.de",
            "192.168.0.40"
        ],
        "datadirectory": "\/var\/www\/owncloud\/data",
        "overwrite.cli.url": "https:\/\/schiedung.ddnss.de\/owncloud",
        "dbtype": "sqlite3",
        "version": "9.1.6.2",
        "logtimezone": "UTC",
        "installed": true,
        "maintenance": false,
        "theme": "",
        "loglevel": 0
    }

Are you using external storage, if yes which one: No

Are you using encryption: No

Are you using an external user-backend, if yes which one: No

LDAP configuration (delete this part if not used)

[Symfony\Component\Console\Exception\CommandNotFoundException]

Client configuration

Browser: Chrome Version 59.0.3071.86 (Offizieller Build) (64-Bit)

Operating system: Ubuntu 16.04