Since yesterday I have a 500 Error on the staging domain of a website in development. Is this a know issue or maybe related with the set in my website?

Hey,
I'm currently working on a client project and I have to add multiple HTML audio players to the page. The audio files are stored in a CMS. The audio elements are easy to set up with a static source but I don't get how I can adjust the src url within a collection and then use the collection item path as well as a base url. Adding it right at src="" doesn't seem to work. Does anybody know how this could work?