Upgrade onlyOffice to 6.1.0/Community Doc Server 0.1.8: not running anymore: http error 500 in settings/onlyOffice after save

Hello
We upgraded to the latest onlyOffice (6.1.0) and Community Document server (0.1.8). Our used nextcloud versions are 20.0.1 (docker latest) or 19 (docker stable).

Onlyoffice was running before this update.

How to produce:
Now, if we press the save button in the “Server settings” block in “Settings/ONLYOFFICE”, we got an http error 500.

We found the following error message in the nextcloud.log with level=3 (=error):
Undefined property: OCA\Onlyoffice\DocumentService::$logger at /var/www/html/custom_apps/onlyoffice/lib/documentservice.php#435

Can we fix this in a configuration or is this a bug?

Thanks for an input in advance
Moritz


Log-Information

nextcloud.log extract
{“reqId”:“u5e69EmrsfppCXPTIg5g”,“level”:3,“time”:“2020-11-03T03:34:10+00:00”,“remoteAddr”:“10.0.0.2”,“user”:“REMOVED-User”,“app”:“PHP”,“method”:“PUT”,“url”:"/apps/onlyoffice/ajax/settings/address",“message”:{“Exception”:“Error”,“Message”:“Undefined property: OCA\Onlyoffice\DocumentService::$logger at /var/www/html/custom_apps/onlyoffice/lib/documentservice.php#435”,“Code”:0,“Trace”:[{“file”:"/var/www/html/custom_apps/onlyoffice/lib/documentservice.php",“line”:435,“function”:“onError”,“class”:“OC\Log\ErrorHandler”,“type”:"::",“args”:[8,“Undefined property: OCA\Onlyoffice\DocumentService::$logger”,"/var/www/html/custom_apps/onlyoffice/lib/documentservice.php",435,{“urlGenerator”:{“class”:“OC\URLGenerator”},“crypt”:{“class”:“OCA\Onlyoffice\Crypt”},“logger”:{“class”:“OC\Log”},“version”:“5.6.5”,“healthcheckResponse”:true,“commandResponse”:{“version”:“5.6.5”,“error”:0,“class”:“stdClass”},“convertedFileUri”:{“0”:“https://REMOVED.ch/apps/onlyoffice/empty?doc=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhY3Rpb24iOiJlbXB0eSJ9.Exth_VdOolI6tgH_RllX9N9SIWQ_9679HYJHTmightM”,“class”:“SimpleXMLElement”},“hashUrl”:“eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhY3Rpb24iOiJlbXB0eSJ9.Exth_VdOolI6tgH_RllX9N9SIWQ_9679HYJHTmightM”,“fileUrl”:“https://REMOVED.ch/apps/onlyoffice/empty?doc=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhY3Rpb24iOiJlbXB0eSJ9.Exth_VdOolI6tgH_RllX9N9SIWQ_9679HYJHTmightM”}]},{“file”:"/var/www/html/custom_apps/onlyoffice/controller/settingscontroller.php",“line”:168,“function”:“checkDocServiceUrl”,“class”:“OCA\Onlyoffice\DocumentService”,“type”:"->",“args”:[{“class”:“OC\URLGenerator”},{“class”:“OCA\Onlyoffice\Crypt”}]},{“file”:"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",“line”:169,“function”:“SaveAddress”,“class”:“OCA\Onlyoffice\Controller\SettingsController”,“type”:"->",“args”:[“https://REMOVED.ch/apps/documentserver_community/”,"","",false,"",false]},{“file”:"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",“line”:100,“function”:“executeController”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Onlyoffice\Controller\SettingsController”},“saveAddress”]},{“file”:"/var/www/html/lib/private/AppFramework/App.php",“line”:152,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Onlyoffice\Controller\SettingsController”},“saveAddress”]},{“file”:"/var/www/html/lib/private/Route/Router.php",“line”:308,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::",“args”:[“SettingsController”,“saveAddress”,{“class”:“OC\AppFramework\DependencyInjection\DIContainer”},{“action”:null,"_route":“onlyoffice.settings.save_address”}]},{“file”:"/var/www/html/lib/base.php",“line”:1009,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->",“args”:["/apps/onlyoffice/ajax/settings/address"]},{“file”:"/var/www/html/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::",“args”:[]}],“File”:"/var/www/html/lib/private/Log/ErrorHandler.php",“Line”:91,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0”,“version”:“20.0.1.1”}

{“reqId”:“u5e69EmrsfppCXPTIg5g”,“level”:3,“time”:“2020-11-03T03:34:10+00:00”,“remoteAddr”:“10.0.0.2”,“user”:“REMOVED-User”,“app”:“index”,“method”:“PUT”,“url”:"/apps/onlyoffice/ajax/settings/address",“message”:{“Exception”:“Exception”,“Message”:“Call to a member function debug() on null”,“Code”:0,“Trace”:[{“file”:"/var/www/html/lib/private/AppFramework/App.php",“line”:152,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Onlyoffice\Controller\SettingsController”},“saveAddress”]},{“file”:"/var/www/html/lib/private/Route/Router.php",“line”:308,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::",“args”:[“SettingsController”,“saveAddress”,{“class”:“OC\AppFramework\DependencyInjection\DIContainer”},{“action”:null,"_route":“onlyoffice.settings.save_address”}]},{“file”:"/var/www/html/lib/base.php",“line”:1009,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->",“args”:["/apps/onlyoffice/ajax/settings/address"]},{“file”:"/var/www/html/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::",“args”:[]}],“File”:"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",“Line”:110,“Previous”:{“Exception”:“Error”,“Message”:“Call to a member function debug() on null”,“Code”:0,“Trace”:[{“file”:"/var/www/html/custom_apps/onlyoffice/controller/settingscontroller.php",“line”:168,“function”:“checkDocServiceUrl”,“class”:“OCA\Onlyoffice\DocumentService”,“type”:"->",“args”:[{“class”:“OC\URLGenerator”},{“class”:“OCA\Onlyoffice\Crypt”}]},{“file”:"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",“line”:169,“function”:“SaveAddress”,“class”:“OCA\Onlyoffice\Controller\SettingsController”,“type”:"->",“args”:[“https://REMOVED.ch/apps/documentserver_community/”,"","",false,"",false]},{“file”:"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",“line”:100,“function”:“executeController”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Onlyoffice\Controller\SettingsController”},“saveAddress”]},{“file”:"/var/www/html/lib/private/AppFramework/App.php",“line”:152,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Onlyoffice\Controller\SettingsController”},“saveAddress”]},{“file”:"/var/www/html/lib/private/Route/Router.php",“line”:308,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::",“args”:[“SettingsController”,“saveAddress”,{“class”:“OC\AppFramework\DependencyInjection\DIContainer”},{“action”:null,"_route":“onlyoffice.settings.save_address”}]},{“file”:"/var/www/html/lib/base.php",“line”:1009,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->",“args”:["/apps/onlyoffice/ajax/settings/address"]},{“file”:"/var/www/html/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::",“args”:[]}],“File”:"/var/www/html/custom_apps/onlyoffice/lib/documentservice.php",“Line”:435},“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0”,“version”:“20.0.1.1”}

Correction with https://github.com/ONLYOFFICE/onlyoffice-nextcloud/commit/4ed51cf2fd6ac52b5b1fe93f8431ec2987f6af2a