Error: 500 Internal Server Error

Sorry, the requested URL 'http://localhost/reader?url=https://cosmonautmag.com/2022/04/the-machiavellian-state-fascism-and-the-tribune-of-the-proletariat/?utm_source=rss&utm_medium=rss&utm_campaign=the-machiavellian-state-fascism-and-the-tribune-of-the-proletariat' caused an error:

Unhandled exception