XF 2.2 Can't edit first post

[Recep Baltaş]

Getting error when trying to edit first post

Uncaught TypeError: Cannot read properties of null (reading 'length')
    at c.prepareInput (prefix_menu.min.js?_v=d5c919a4:8:151)
    at c.setupSelect2 (prefix_menu.min.js?_v=d5c919a4:13:90)
    at HTMLSelectElement.i (jquery.min.js:2:88736)
    at HTMLSelectElement.dispatch (jquery.min.js:2:43090)
    at v.handle (jquery.min.js:2:41074)
    at Object.trigger (jquery.min.js:2:71513)
    at HTMLSelectElement.<anonymous> (jquery.min.js:2:72108)
    at Function.each (jquery.min.js:2:2976)
    at S.fn.init.each (jquery.min.js:2:1454)
    at S.fn.init.trigger (jquery.min.js:2:72084)

This began after updating:

• Report Center Essentials
• Cloudflare App
• Multi Prefix

Which one could be the problem?

Update: Got it. It's Multi Prefix.