Unable to add customer addresses in the backend

[Pillepalle909]

I am desperately trying to add addresses for a customer account in the backend. The corresponding input window opens and I can also enter all the data. However, when I press save, the window reloads, but the data has not been processed.

Does anyone have any idea what the problem could be?

These are the errors that the console spits out in Chrome:

Quote

JQMIGRATE: Migrate is installed with logging active, version 3.4.0 // main.bundle.js:604

JQMIGRATE: 'ready' event is deprecated // o @ main.bundle.js:604
setup @ main.bundle.js:604
add @ main.bundle.js:660
(anonymous) @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
(anonymous) @ main.bundle.js:660
each @ main.bundle.js:649
each @ main.bundle.js:649
Se @ main.bundle.js:660
on @ main.bundle.js:660
(anonymous) @ ps_emailalerts.js:20

Vue app mount element or context not found // index.js:184
(anonymous) @ index.js:184
(anonymous) @ index.js:2
(anonymous) @ index.js:1672

JQMIGRATE: jQuery.isArray is deprecated; use Array.isArray // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
t.define.Y._resolveLanguage @ main.bundle.js:636
t.define.Y.applyFromElement @ main.bundle.js:636
s @ main.bundle.js:636
e @ main.bundle.js:636
(anonymous) @ main.bundle.js:636
each @ main.bundle.js:649
each @ main.bundle.js:649
t.define.e.fn.select2 @ main.bundle.js:636
(anonymous) @ main.bundle.js:666
each @ main.bundle.js:649
each @ main.bundle.js:649
initSelect2 @ main.bundle.js:666
(anonymous) @ main.bundle.js:666
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.click() event shorthand is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
V @ main.bundle.js:871
(anonymous) @ main.bundle.js:896
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.hover() is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
(anonymous) @ main.bundle.js:2065
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.bind() is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
(anonymous) @ admin.js?v=8.1.5:811
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.submit() event shorthand is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
(anonymous) @ tools.js?v=8.1.5:749
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.change() event shorthand is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
slectType @ back.js:150
(anonymous) @ back.js:42
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660

JQMIGRATE: jQuery.fn.keyup() event shorthand is deprecated // main.bundle.js:604
o @ main.bundle.js:604
t.<computed> @ main.bundle.js:604
baseSearchProduct @ back.js:77
(anonymous) @ back.js:45
u @ main.bundle.js:660
c @ main.bundle.js:660
setTimeout (async)
(anonymous) @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
fire @ main.bundle.js:660
l @ main.bundle.js:660
fireWith @ main.bundle.js:660
ready @ main.bundle.js:660
q @ main.bundle.js:660
new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740 
     
      
GET https://kleine-muehle.com/admin/index.php/_wdt/128486?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME 500 (Internal Server Error)
request @ new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740
load @ new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740
loadToolbar @ new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740
(anonymous) @ new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740
(anonymous) @ new?_token=OvrCjiZmlyK092qAYtH9hZQRdWKnkBnZQFLlZcgmLME:1740
index.js:154

API Schema is not valid: SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON
fetchInitialDatas @ index.js:154
await in fetchInitialDatas (async)
(anonymous) @ index.js:10
(anonymous) @ index.js:182
(anonymous) @ index.js:6
(anonymous) @ index.js:6
runWithContext @ index.js:2
C @ index.js:6
(anonymous) @ index.js:6
Promise.then (async)
(anonymous) @ index.js:6
fe @ index.js:6
(anonymous) @ index.js:6
Promise.then (async)
I @ index.js:6
$ @ index.js:6
m @ index.js:6
install @ index.js:6
use @ index.js:2
(anonymous) @ index.js:184
(anonymous) @ index.js:2
(anonymous) @ index.js:1672

JQMIGRATE: jQuery.fn.unbind() is deprecated // main.bundle.js:604

[Pillepalle909]

As soon as the debug mode is active and I call up any page in the backend, "An error occurred while loading the web debug toolbar." is displayed continuously in the bar at the bottom left. Presumably this is somehow related, but unfortunately I can't figure out how to fix the error myself.