Impersonate not working

[lewmilburn]

Steps to reproduce

1. Go to users as an admin
2. Click impersonate icon

Expected behaviour

Should impersonate a user

Actual behaviour

Nothing

Server configuration

Operating system: Linux

Web server: Apache

Database: mySQL

PHP version: 7.2

ownCloud version: 10.4.0

Updated from an older ownCloud or fresh install: Fresh

Where did you install ownCloud from: ownCloud Installer

Signing status (ownCloud 9.0 and above):

https://gist.github.com/lewmilburn/7989f129aca7b163788aeb051ed8ba23

The content of config/config.php:

<?php
$CONFIG = array (
  'instanceid' => 'removed',
  'passwordsalt' => 'removed',
  'secret' => 'removed',
  'trusted_domains' => 
  array (
    0 => 'www.removed',
    1 => 'removed',
  ),
  'maintenance' => false,
  'datadirectory' => 'removed',
  'overwrite.cli.url' => 'removed',
  'dbtype' => 'mysql',
  'version' => '10.4.0.4',
  'lost_password_link' => 'removed/reset',
  'dbname' => 'removed',
  'dbhost' => 'localhost',
  'dbtableprefix' => 'removed',
  'dbuser' => 'removed',
  'dbpassword' => 'removed',
  'logtimezone' => 'UTC',
  'theme' => 'MyCloud',
  'apps_paths' => 
  array (
    0 => 
    array (
      'path' => 'removed/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 => 
    array (
      'path' => 'removed/apps-external',
      'url' => '/apps-external',
      'writable' => true,
    ),
  ),
  'installed' => true,
  'mail_domain' => 'removed',
  'mail_from_address' => 'noreply',
  'mail_smtpmode' => 'php',
);

Are you using external storage, if yes which one: local

Are you using encryption: no

Are you using an external user-backend, if yes which one:

Client configuration

Browser: Edge (Chromium / DEV)

Operating system: Windows 10

Logs

Web server error log

Nothing in log since error started.

ownCloud log (data/owncloud.log)

Nothing in log since error started.

Browser log

jquery.js:8630 POST https://www.themycloud.co.uk/open/index.php/apps/impersonate/user 406
send @ jquery.js:6981
ajax @ jquery.js:6981
n.<computed> @ jquery.js:6981
impersonate @ impersonate.js?v=b2df45156f44ca90d05bc052ea003b0a:93
(anonymous) @ impersonate.js?v=b2df45156f44ca90d05bc052ea003b0a:115
dispatch @ jquery.js:3761
r.handle @ jquery.js:3761
impersonate.js?v=b2df45156f44ca90d05bc052ea003b0a:99 Uncaught TypeError: Cannot read property 'error' of undefined
    at Object.<anonymous> (impersonate.js?v=b2df45156f44ca90d05bc052ea003b0a:99)
    at j (jquery.js:3099)
    at Object.fireWith [as rejectWith] (jquery.js:3211)
    at x (jquery.js:8266)
    at XMLHttpRequest.<anonymous> (jquery.js:8605)