I just created a new test site for myself and upgraded to Moodle 3.11.1+. I run Moodle through my XAMPP application from Apache Friends. I got a strange exception when I went into the Theme Selector and clicked on "Change Theme" in the Default device type. This is what I got:
Has this happened to anyone else? How would I go about fixing this? Unfortunately I'm not well-versed so I'm not even too sure what this means.