[WPMU DEV Dashboard] Cannot activate plugins

I cannot activate, update or deactivate any plugins using the WPMU DEV Dashboard. Every time I try it, the site freezes, to fix which I have to restart the server.

The whole site stops functioning, and when I try to load any page, it keeps loading for ages and ends up with a 504 Gateway Timeout. Please note that I can do all of this using the default WordPress Plugins page without an issue.

We enabled WP_DEBUG, but no debug.log was generated. I had an error log and some relevant error messages have been attached in the chat transcript. I was also able to see some errors in the browser console, a screenshot of which I have attached in the chat transcript as well. Please advice.