Mail Builder no response with templates

Your software
My Mautic version is: 4.4.11
My PHP version is: 8.0.28
My Database type and version is: mariadb Ver 15.1 Distrib 10.6.12-MariaDB

Your problem
My problem is: I get an 500 Server error after selecting the standard mail template. Because of this I can not edit the templates with the internal mail builder.

These errors are showing in the log:

   GET https://[]/s/grapesjsbuilder/email/2?template=brienz&_=1709275640198&mauticUserLastActive=1340&mauticLastNotificationId= 500 (Internal Server Error)
        send @ libraries.js?veaae2d53:766
        ajax @ libraries.js?veaae2d53:744
        l @ builder.js:44
        (anonymous) @ app.js?veaae2d53:186
        dispatch @ libraries.js?veaae2d53:465
        elemData.handle @ libraries.js?veaae2d53:451

builder.js:65 setThemeHtml - Request failed: error

Hi, is this upgraded or fresh install?
Is it Softaculus install?

Hey joeyk, thank you for your reply!

It is/was installed on aws via bitnami on version 4.4.6 and then I updated it via shell to the latest 4.x version.

when I select a template, despite of the error and then open the mail builder I get these errors in the browser console:

Uncaught Error: No valid HTML template found
at n.getOriginalContentHtml (content.service.js:119:13)
at l.value (builder.service.js:205:39)
at l.value (builder.service.js:107:28)
at Object.t [as launchBuilder] (builder.js:33:11)
at HTMLButtonElement.onclick (2:3490:220)
at Object.trigger (libraries.js?veaae2d53:683:90)
at HTMLButtonElement. (libraries.js?veaae2d53:688:258)
at Function.each (libraries.js?veaae2d53:153:170)
at jQuery.fn.init.each (libraries.js?veaae2d53:144:192)
at jQuery.fn.init.trigger (libraries.js?veaae2d53:688:229)