Those are the errors and warnings that appear in the server log:
2021-12-16 15:18:11 Error 142.... 500 GET /index.php/esp/$$$call$$$/grid/notifications/task-notifications-grid/fetch-grid HTTP/1.0 Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Safari/605.1.15 435 Apache SSL/TLS access
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: PHP Fatal error: Uncaught Error: Call to a member function getId() on null in /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/controllers/grid/notifications/TaskNotificationsGridHandler.inc.php:40 Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: Stack trace: Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: #0 /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/classes/controllers/grid/GridHandler.inc.php(314): TaskNotificationsGridHandler->loadData(Object(Request), NULL) Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: #1 /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/classes/controllers/grid/GridHandler.inc.php(1030): GridHandler->getGridDataElements(Object(Request)) Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: #2 /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/classes/controllers/grid/GridHandler.inc.php(921): GridHandler->renderGridBodyPartsInternally(Object(Request)) Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: #3 /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/classes/controllers/grid/GridHandler.inc.php(643): GridHandler->doSpecificFetchGridActions(Array, Object(Request), Object(TemplateManager)) Apache error
2021-12-16 15:18:11 Warning 142.... mod_fcgid: stderr: #4 /var/www/vhosts/empirische-sonderpaedagogik in /var/www/vhosts/empirische-sonderpaedagogik.de/httpdocs/jm/ojs/lib/pkp/controllers/grid/notifications/TaskNotificationsGridHandler.inc.php on line 40 Apache error
and this from the Chrome inspector.
first entry:
GET /index.php/esp/$$$call$$$/page/page/tasks?_=1639663670396 HTTP/1.1
Host: empirische-sonderpaedagogik.de
Connection: keep-alive
sec-ch-ua: "Chromium";v="97", " Not;A Brand";v="99"
Accept: application/json, text/javascript, */*; q=0.01
X-Requested-With: XMLHttpRequest
sec-ch-ua-mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4673.0 Safari/537.36
sec-ch-ua-platform: "Windows"
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://empirische-sonderpaedagogik.de/index.php/esp/submissions
Accept-Encoding: gzip, deflate, br
Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
Cookie: OJSSID=83...
HTTP/1.1 200 OK
Server: nginx
Date: Thu, 16 Dec 2021 14:29:01 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: keep-alive
Vary: Accept-Encoding
X-Powered-By: PleskLin
Content-Encoding: br
second entry:
GET /index.php/esp/$$$call$$$/grid/notifications/task-notifications-grid/fetch-grid?_=1639663670397 HTTP/1.1
Host: empirische-sonderpaedagogik.de
Connection: keep-alive
sec-ch-ua: "Chromium";v="97", " Not;A Brand";v="99"
Accept: application/json, text/javascript, */*; q=0.01
X-Requested-With: XMLHttpRequest
sec-ch-ua-mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4673.0 Safari/537.36
sec-ch-ua-platform: "Windows"
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://empirische-sonderpaedagogik.de/index.php/esp/submissions
Accept-Encoding: gzip, deflate, br
Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
Cookie: OJSSID=83...
HTTP/1.1 500 Internal Server Error
Server: nginx
Date: Thu, 16 Dec 2021 14:29:02 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 0
Connection: keep-alive