If you get an error like:

URL was not parsed due to an ODataUnrecognizedPathException. Resource not found for the segment provided in the URL.

… when you’re trying to reference an entity set, it’s likely you’ve fallen afoul of Microsoft’s pluralisation. Your problem starts when you try to do things right.

Which is odd, when the Entity Framework team have done a great job in their pluralisation of entities, so:

But in Power Apps, we turn into Gollum:

Don’t forget that custom Entity Sets need their own special treatment. eg. /my_contactses(4a4c3026-495a-45be-ab8d-09c0da6f912b).